
Book_ 



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GopyrigM 



I L- 



CjQZffilGKT DEPOSIT 



ELEMENTS 



OF 



INDUSTRIAL CHEMISTRY 



BY 

ALLEN ROGERS 

In charge of Industrial Chemistry, Pratt Institute, Brooklyn, N. Y. 

» 

An Abridgment of 

Manual of Industrial Chemistry 

Written by Forty Eminent Specialists and Edited 
By ALLEN ROGERS 



117 ILLUSTRATIONS 




NEW YORK 

D. VAN NOSTRAND COMPANY 

25 Park Place 

1916 






Copyright, 1916, by 
D. VAN NOSTRAND COMPANY 



4i 



0*L 



NOV 24 I9IS 



JCI.A4 485G7 



3 



PREFACE 



The purpose in presenting this elementary work on Industrial 
Chemistry is to meet the needs of those teachers of the subject 
who find that the time at their disposal does not warrant the 
employment of an extended treatise. The author, therefore, 
has compiled from the Manual of Industrial Chemistry an 
abridged volume which covers the most salient points of the 
larger book. The endeavor has been, in arranging this con- 
densation, to treat the subjects covered in a general manner 
only, thus eliminating as much of the detail as possible in order 
that the fundamental principles might be more clearly set forth. 

Although the subject matter is essentially descriptive, a 
certain amount of theoretical consideration has been included 
where necessary for the proper understanding of the text. Should 
the student desire more detailed information on the subject, 
or a more extended description of the processes under con- 
sideration he is referred to the Manual from which this book 
is compiled. No claim for originality is made for this volume, 
and full credit should be given to those who contributed to the 
larger book mentioned above. 

The book as it now stands consists of twenty-seven chapters 
covering a somewhat limited range of subjects, but at the same 
time is sufficiently broad to give the student a very compre- 
hensive view of the entire field. 

Allen Rogers. 
Pratt Institute, Brooklyn, N. Y. 
September 20, 1916. 



CONTEXTS 



PAGE 

General Processes Chapter I 1 

Grinding — Crushing — Crushers — Mills — Disintegrator — 
Pulverizer — Sifting — Sedimentation — Levigation — Filtration — 
Filter Press — Centrifugal machine— Lixiviation — Extraction — Crys- 
tallization — Calcination — Furnaces — Kilns — Evaporators — 
Kettles — Refrigeration. 

Water, Its Uses and Purification Chapter II 30 

Natural waters — Boiler waters — Scale formation — Incrustation — 
Corrosion — Foaming — Purification of water — Numerical standards — 
Classification — Potable waters — Sand nitration — Boiler compounds. 

Fuels Chapter III 49 

Wood — Peat — Lignite — Bituminous coal — Briquettes — Anthra- 
cite — Charcoal — Water gas — Coal gas — Oil gas — Natural gas. 

Sulphuric Acid Chapter IV 65 

Occurrence — Raw materials — Outline of process — Glover tower 
— Gay-Lussac tower — Sulphur burning — Furnaces — Pyrites — 
Burners — Dust prevention— Chamber system — Kestner lifts — Acid 
eggs — Platinum stills — Contact process — Silica stills. 

Nitric Acid Chapter V 91 

Occurrence — Properties — Manufacturing processes. 

Elements and Inorganic Compounds Chapter VI 106 

A short description of over 300 elements and compounds with 
a brief account of their commercial application. 

Ceramic Materials and Products Chapter VII 177 

Lime — Kilns — Mortar — Cement — Limestone — Marl — Clays — 
Plaster of Paris — Kaolin — Bricks — Tile — Pottery — Stoneware — Por- 
celain — Glass. 

v 



vi CONTENTS 

PAGE 

Pigments Chapter VIII 203 

White Lead — Sublimed white lead — Zinc oxide — Lithopone — 
Barytes — Whiting — Asbestine — Gypsum — Red pigments — Blue pig- 
ments — Yellow pigments — Black pigments — Lakes. 

Fertilizers Chapter IX 219 

Raw materials — Blood — Tankage — Guano — Cyanamide — Fish 
scrap — Phosphate rock — Thomas slag — Belgian slag — Bone — 
Potash. 

Illuminating Gas Chapter X 231 

Coal gas — Retorts — Hydraulic Main — Condensers — Tar Extract- 
ors — Exhausters — Scrubbers — Purifiers — Water gas — Lowe appa- 
ratus — Williamson machine — All-oil water gas — Pintsch gas — Blau 
gas — Acetylene. 

Coal Tar and Its Distillation Products Chapter XI 247 

Coal tar — Retort gas tar — Oven gas tar — Producer gas tar — Blast 
furnace tar — Water gas tar — Pintsch gas tar — Creosote oil — Cresol — 
Benzene — Toluene — Naphthalene — Anthracene. 

The Petroleum Industry Chapter XII 262 

Petroleum — Origin — Constitution — Locality — Production — Dis- 
tillation — Asphalt — Shale oil — Ozokerite . 

The Destructive Distillation of Wood Chapter XIII 277 

Preparatory treatment — Distillation — Retorts — Condensers — 
Rosin process — Hot water process — Extraction process — Wood 
alcohol — Acetone. 

Oils, Fats and Waxes Chapter XIV 290 

Classification — Constitution — Vegetable oils — Animal oils — Fish 
oils — Waxes. 

Lubricating Oils Chapter XV 317 

Choice of oils — Watch oils — Spindle oils — Loom oils — Engine 
oils — Crank case oils — Greases — Belt dressings — Reduced oils — 
Soluble oils. 



CONTENTS vii 

PAGE 

Soap, Soap Powder, and Glycerine Chapter XVI 323 

Classification — Boiling — Graining — Framing — Slabbing — Finish- 
ing — Boiled toilet — Milling — Plodding — Pressing — Half boiled — Soft 
soap — Floating- — Powders — Glycerine. 

Essential Oils Chapter XVII 340 

Crude distillation — Modern distillation — Steam distillation — Ex- 
pressed oils — Macerating process — Enflurage process — Flower po- 
mades — Volatile solvents — Absolutes — Chemical constitution — Oils. 

Resins, Oleo-resins, Gum-resins, Gums Chapter XVIII 362 

Sources— Constitution — Gums — Resins — Rubber. 

Varnish Chapter XIX 370 

Definition — Classes — Outfit for making varnish — Spirit varnishes 
— Oil varnishes — Baking varnishes — Japan driers. 

Sugar Chapter XX 381 

Raw materials — Cane sugar — Extraction process — Defecation 
process — Beet sugar — Sugar refining. 

Starch, Glucose, Dextrin and Gluten Chapter XXI 395 

Classification — Sources — Methods of manufacture — Drying — Al- 
kaline starches— Grape sugar — Dextrin — British gum. 

Beer, Wine and Liquor Chapter XXII 406 

Malting — Brewing — Grapes — The Must — Fermentation — Distil- 
lation. 

Textiles Chapter XXIII 429 

Origin — Animal fibers — Vegetable fibers — Mineral fibers — Arti- 
ficial fibers — Bleaching. 

Dyestuffs and their Application Chapter XXIV 447 

Textile coloring — Textile printing — Dyeing — Staining — Mordant 
colors — Acid colors — Basic colors — Natural colors — Azo-colors — Vat 
colors. 

The Paper Industry Chapter XXV 459 

Rag paper — Wood paper — Mechanical process — Soda proeess — 
Sulphite process. 



Yin 



CONTENTS 



PAGE 

...Chapter XXVI 470 
powders — Nitrogly- 



Explosives 

Black powder— Nitrocellulose— Smokeless 
cerine— Dynamite— Fulminates. 

Chapter XXVII 481 

Leather 

Raw materials-Soaking-Depilation-Bating-Chrome tannage 
—Vegetable tannage— Alum tannage— Formaldehyde tannage- 
Patent leather. 



ELEMENTS OF INDUSTRIAL CHEMSTEY 



CHAPTER I 
GENERAL PROCESSES 

GRINDING. In the manufacture of chemical products, 
one of the most important operations is that of grinding. Not 
only is it often necessary to reduce the raw material to a state 
of fine division before it can be used, but the finished product, 
in many instances, must be placed on the market in the form of 
a fine powder or paste. The result to be secured depends entirely 
upon the nature of the product or material and the purpose for 
which it is to be employed. Thus in many metallurgical opera- 
tions it becomes necessary to crush very hard rocks or ores; 
while on the other hand some materials, like pigments, must be 
sold as a very fine powder. Therefore, we have two general 
divisions of grinding machines — those which are used for crushing 
or coarse grinding and those which are used for producing a fine 
powder. For those materials which appear on the market in the 
form of a paste, special forms of grinding machines are employed. 
The following are some of the types of grinding machinery: 

JAW CRUSHER. 1 The simplest and least expensive form of 
crusher in use is that known as the jaw crusher. It is a very 
heavy type of machine and consists essentially of a stationary steel 
plate against which a corresponding steel jaw works on a cam, 
thus giving a rolling motion. The working parts may be regu- 
lated by means of an adjusting screw so as to give a coarse or 
fine product as desired. This machine is capable of crushing the 
hardest of materials. It finds extensive application in metal- 
lurgical operations where ores are to be crushed; in the manufac- 
ture of plaster of Paris; in crushing of pyrites for sulphuric acid 

1 Sturtevant Mill Co., Boston, Mass. 



2 ELEMENTS OF INDUSTRIAL CHEMISTRY 

manufacture and for many other purposes. On account of the 
strain this machine is always placed on a very solid foundation. 

Fig. 1 represents a small-size jaw crusher used for laboratory 
work which may be either hand or power driven. Fig. 2 illus- 




Fig. 1. 




Fig. 2. 



trates a heavy machine employed in crushing pyrites for the 
manufacture of sulphuric acid. 

CRUSHING ROLLS. 1 This type of machine is employed quite 
extensively for reducing the product of the jaw crusher to a finer 
state of division. Fig. 3 shows a laboratory roller, while Fig. 4 
'Sturtevant Mill Co., Boston. Mass. 



GENERAL PROCESSES 3 

illustrates a heavy type of machine used in metallurgical opera- 
tions. The rolls may be either plain or corrugated. These 
machines are also employed for crushing soft materials. Fig. 5 
represents a battery of rollers used in crushing sugar cane, while 




Fig. 3. 




Fig. 4. 

Fig. 6 is a form used extensively for crushing seeds such as flax- 
seed in the manufacture of linseed oil. 

ROTARY FINE CRUSHER. 1 For rocks of moderate hard- 
ness the rotary crushers are almost universally employed. These 
1 Sturtevant Mill Co., Boston, Mass. 



ELEMENTS OF INDUSTRIAL CHEMISTRY 







GENERAL PROCESSES 5 

machines are provided with double doors that carry all of the 
grinding parts and swing open as easily as the doors of a safe, 
thus exposing every part to inspection. They are built with 
capacities of from 2 to 30 tons per hour. They may be regulated 
while running for fine or coarse work by turning the adju ting 
wheel. Fig. 7 represents such a mill, which finds extensive 
application in the grinding of cement rock. 

CHASER. 1 There are many materials which, owing to their 
peculiar nature, cannot be crushed by means of the machines 




r\ 





Fig. 7. 



Fig. 



described above. Such substances as drugs, clays, and putty 
are handled in the chaser. It is also employed in mixing bams 
for use in the foundry, for mixing mortar and for mixing and 
grinding to a semi-dry state. The chaser is constructed with a 
stone or steel bed on which rotates one or two " edge runners " 
or " travelers." An arm provided with a scraper travels 
just in front of the runners, which brings the material under 
the heavy rollers, while the whole is set in a pan arranged with a 
gate for discharging. Fig. 8 shows such a machine. 

1 Chas. Ross & Sons Co., Brooklyn, N. Y. 



6 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



DISINTEGRATOR. 1 This type of machine, also known as 
pulverizing mill, is especially adapted for such materials as are 
of a lumpy nature, such as dry colors, soft pigments, borax, sul- 
phur, starch, etc. ; also for mixing dry materials, such as fertilizers, 
for example. The construction of this machine is very simple, 




Fig. 9. 




Fig. 10. 



as will be seen from Figs. 9 and 10. The steel cages run at a very 
high speed in opposite directions, thus driving the material 
through the steel bars by centrifugal force, and pounding it to 
a powder. They are strongly built, and may be easily 
and quickly cleaned by taking off the top half of the casing, 
1 Chas. Ross & Sons Co., Brooklyn, N. Y. 



GENEEAL PEOCESSES 



removing the bolts holding bearing frames to bed plate, then 
drawing frame and cages apart by tail screw, as shown in the 
illustration. 

BUHR STONE MILL. 1 For the fine grinding of dry or wet 
materials this type of mill is in very common use. Fig. 11 shows 
an under-driven dry mill, which is open in order to give an idea 
of the grinding surfaces. This mill is employed for the grinding 
of soft materials such as flour, pigments and dry colors. Fig. 12 





Fig. 11. 



Fig. 12. 



is the Ross improved paint and color mill ready for work. This 
mill is provided with a double set of stones having a water- 
cooling arrangement to prevent excessive generation of heat in 
the grinding of paste colors and paints. In using these mills 
the material is fed in through the hopper and by centrifugal 
force is carried to the grinding parts of the first set of stones, 
from which it then passes to the second set. The degree of 
fineness is regulated by means of set screws on the side. For 
paste and paint grinding it is necessary to provide a scraper on 
1 Chas. Ross & Sons Co., Brooklyn, N. Y. 



8 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



the traveling stone to remove the product as it passes the 
grinding face. 

BALL MILL. There are many types of these mills on the 
market which find application in various lines of industry. Among 
the most commonly used of these mills might be mentioned the 
Fuller-Lehigh pulverizer, Fig. 13, largely employed in the manu- 
facture of cement, which consists of a horizontal ring or die against 
which revolve four balls. The balls are propelled by means of 
pushers. The die and pushers are chilled charcoal-iron castings. 

The balls are of steel forgings. They 
revolve at a speed of about 155 R.P.M., 
and hence press against the die with 
enormous centrifugal force. The ma- 
terial to be ground is fed into the 
hopper which serves the feeder. The 
material discharged by the feeder falls 
down into the pan of the mill, situated 
below the die, and is drawn up from 
this in between the rapidly revolving 
balls and stationary die by means of 
air currents induced by fans placed in 
the chamber above the die. The ma- 
terial is pulverized by the rolling of the 
ft^^^^ G^lifeo balls against the die, the grinding action 
being similar to that of a mortar and 
pestle. The finely pulverized material 
is sucked upwards by means of the fans 
and out through the screens. The ma- 
terial passing through the screen falls 
down between this screen and the outer 
casing, and is discharged from the mill 
through the discharge spout, which may 
be placed at any one of four quarters of the mill. The feed to the 
mill and consequently the fineness of the product, may be con- 
trolled in two ways — either by a slide on the hopper or by means 
of the stepped pulley, connected to the screw conveyor by gearing. 
The mill is provided with two screens, one — the inner — of 1-in. mesh 
and made of very heavy wire to protect the outer one. The outer 
screen does not really screen, but merely controls the draft of 
air, and hence the fineness, since the greater the velocity the 
greater the carrying power of the air, and hence the coarser the 
product. 




GENERAL PROCESSES 9 

The Griffin mill is somewhat similar to the Fuller-Lehigh 
mill in operation. It consists of a steel die against which a roll 
also of steel is made to revolve, and it is between these two that 
the material is ground. The roll is suspended by a shaft from 
a spider, and actuated by a pulley and a universal joint. The 
fully ground material is sucked up and forced through the screens. 
The coarse particles fall back into the pans of the mill and are 
thrown up between the roll and the die by means of a plow 
attached to the roll. The finished product passes through the 




Fig. 14. 



screen and travels from these to the outer casing and thence 
through openings in the base of the mill to screw conveyors. 

PEBBLE MILLS. 1 Pebble mills grind principally by friction, 
the effect being produced by the sliding, tumbling and rolling- 
inside of the mill of a great number of flint pebbles or porcelain 
balls which are mixed with the substance to be ground. The 
movement is caused by revolving the mill at a regulated speed. 
As pebble mills are not crushers, all material should be crushed 
to a certain degree of fineness before being charged into the 
machine. The mill shown in Fig. 14 is lined with vitrified por- 

1 Abbe Engineering Co., New York City. 



10 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



celain, thus presenting a grinding surface which will neither 
contaminate nor discolor the material being pulverized. 

TUBE MILLS. The general principle of grinding employed 
by the tube mill is the same as in the ordinary pebble mill, the 
difference being that the material to be ground in the tube mill 
is fed in at one end and is delivered as a finished product at the 
other, the fineness of the product being regulated simply by the 
speed at which the material is fed into the machine. The slower 
the feeding the longer the material receives the action of the 
pebbles and the finer the discharged product will be. To make 
a coarse material the feeding is increased. 

Some of the more modern forms of tube mills are provided 




Fig. 15. 



with a " spiral feed." By means of a crescent-shaped opening 
located where the spiral starts, a certain quantity of the material 
is allowed to enter, and as the machine revolves this travels 
forward until it reaches the center, where it enters the grinding 
chamber. Thus after two or three revolutions there is a constant 
feed of a regular amount of material. From the grinding chamber 
the product passes through a perforated plate into a reverse 
spiral and thence is discharged from the center of the machine. 
In this way all labor of shoveling pebbles is avoided. 

ROLLER MILLS. 1 For the grinding of lithographic inks, 
colors in varnish, chocolate and many other pasty materials the 

1 Chas. Ross & Sons Co., Brooklyn, N. Y. 



GENERAL PROCESSES 11 

above methods cannot be satisfactorily employed. The roller 
mill, Fig. 15, obviates the difficulties encountered and is largely 
used for the purposes mentioned. In their construction these 
machines usually consist of three steel rolls, which rotate at 
different speeds, thus passing the product to the front, where 
it is detached by means of a scraper, and falls onto the apron. 
By means of adjusting wheels the front and back rolls are 
under perfect control, and may be set to any degree of fineness 
desired. 

SIFTING. In those instances where the substance being 
treated is ground in a dry condition, it is often necessary to 
separate the coarse from the fine material. This is accomplished 
by the use of sifting or bolting machines, there being numerous 
forms and styles employed for the purpose. The degree of fine- 
ness is regulated by using either wire sieves or bolting cloth. In 
all cases the ground material enters the reel, and as this rotates 
the fine powder passes through the meshes, leaving the coarse 
particles in the reel. 

SEDIMENTATION. In order to overcome the annoyance 
and loss caused by flying dust, many materials are ground in 
water. As the resulting turbid liquid comes from the mill it is 
allowed to flow into the first of a series of tanks, where the coarser 
and heavily particles rapidly subside, leaving the finer substance 
in suspension. The liquid is then drawn to the second tank, 
where it is allowed to remain somewhat longer than in the first 
tank. In each of the subsequent tanks the liquid is allowed to 
remain for a longer period than in the one previous, thus giving 
various degrees of fineness to the resulting product, the coarse 
particles being returned to the mill for further grinding. This 
operation is sometimes spoken of as " levigation." 

FILTRATION. By this process is meant the separation of 
suspended solids from a liquid, and often presents grave difficul- 
ties; especially is this so when working with large volumes. The 
medium employed may be paper, cloth, cotton, wool, asbestos, 
slag or glass-wool, unglazed earthenware, sand or other porous 
material. 

RIBBED FILTER. For handling small amounts of material 
the ribbed filter is very convenient, and consists in folding an 
ordinary large filter in such a manner that when inserted into the 
funnel it will leave canals along the side. To prevent breaking 
of the filter the tip should be forced well into the neck of the 
funnel. 



12 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



BAG FILTER. A very satisfactory method of filtering coarse 
material is to arrange four pieces of wood as shown in Fig. 16, 
and on the brads suspend a piece of muslin 
in such a manner as to form a bag. The 
portion passing through at first may be 
slightly cloudy, but as the pores fill with 
the precipitate the filtrate becomes clear. 

Suction Filter. This form of filter 
is used very largely where it is desired to 
retain the filtrate as well as the solid 
matter. It consists of a box arranged so 
that the lower section is connected with the 
vacuum pump, and over the perforated 
bottom is placed canvas or other filtering 
medium. 

FILTER PRESS. A very rapid and con- 
venient method of filtration is by means of the filter press. 
Although they are all built on the same principle, their details of 
construction vary to a marked degree. In its simplest form, how- 





Fig. 17. 



ever, it consists of distance frames and plates. These plates and 
frames rest upon a pair of parallel bars, and are held in position by 
means of lugs projecting from each side. Over the surface of each 
plate is stretched a filtering medium, usually cloth, which is held in 



GENERAL PROCESSES 



13 



place by means of pegs, the whole being forced against the adjacent 
frame by means of a screw or hydraulic pressure. The material 
to be filtered is forced through the channel along the top of the 
press and into the distance frames. The solid material is held 
back by the filtering medium, gradually filling the chambers and 
producing a solid cake. The liquid which passes through the 
filter is allowed to discharge into the channels along the lower por- 
tion of the press, where it may be recovered or discarded as wished. 
A more recent form of filter press is the Sweetland self-dump- 




Fig. 18. 



ing filter, shown in Fig. 17. The material to be filtered is forced 
into the filter body by gravity pressure or by means of a pump. 
The filter body comprises two semi-cylindrical castings of high 
tensile strength. As soon as the filter body is filled, the pressure 
rises, causing the liquid portion to pass through the filter cloth, 
while the solid matter is deposited on the leaf in a compact form. 
When the filter is full the bottom half of the body is lowered, 
and then by reversing the pressure the cake is easily and very 
quickly detached. 

Centrifugal Machine. 1 This appliance is used for sepa- 

1 American Tool and Machine Co., Boston, Mass. 



14 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



rating liquids from solids. It is especially adapted to the drying 
of crystals in that it throws off the adhering mother liquor by 
centrifugal force. It is also employed for drying yarns, textiles, 
wood pulp, sugar, starch, etc. The centrifuge, therefore, is used 
more as a means of drying than of filtration. It consists of a 
cylindrical perforated basket fixed to a vertical shaft, which 
rotates at a very high speed (900 to 1200 revolutions per minute), 
Fig. 18. * By means of the centrifugal force generated the contents 
of the basket are driven to the outer wall, where the solid material 
is detained, and the liquid thrown off. In working with the 




Fig. 19. 



machine great care must be exercised lest grave accidents occur. 
It is also necessary to see that the machine is carefully con- 
structed. 

DRYING. Before submitting material to the dr3 7 ing process 
proper it may be advantageous to remove as much of the adher- 
ing liquid as possible by draining, filtering, or centrifuging. The 
water that still adheres is now removed by evaporation in contact 
with the air at as high a temperature as compatible with the 
substance and economical practice. Whenever waste heat is 
available it should be used. 

In order that drying should be uniform the substance to be 
dried is stirred, usually by mechanical appliances. The simplest 



GENERAL PROCESSES 15 

arrangement would consist of a platform of metal or stoneware 
heated by flue gases and upon which the material would be spread 
and stirred from time to time; this is not, however, an economical 
process. A less wasteful method is by the use of drying chambers, 
built of brick, wood, or metal. The chamber may be heated 
from the inside, or the air passing through it may be heated. 
To aid in the removal of the moist air an exhaust or fan is usually 
employed. 

Where temperatures of 100° C. or less are desired the air may 
be heated by passing it over steam-heated coils, or the plate on 
which the material is placed may have a steam-heated jacket. 
As the point at which the heat enters the apparatus, be it steam 
or flue gases, is the point of greatest heat, it is usual to provide 
for the conveying of the material from the further and cold end 
of the apparatus toward the hottest portion. For this purpose 
the shaft furnace can be used, provided the material is hard 
enough and there is no need of regulating the temperature very 
carefully. A large number of more or less efficient forms of 
dryers are manufactured, among which vacuum dryers, in which 
the drying is done at a considerable saving of labor, fuel and 
time, are the most important. Vacuum dryers may be divided 
into shelf dryers, Fig. 19, for material that does not need to be 
stirred while drying; rotary dryers for material which must be 
continuously stirred; and drum dryers for substances like glue, 
which readily forms a dry film on the surface. 

LlXTVIATlON. The process of lixiviation consists in the 
separation of water-soluble material from insoluble or less soluble 
material. The substance to be treated with water may be sus- 
pended in bags or baskets, or placed in tanks provided with 
perforated false bottoms. The solution, being denser than water, 
sinks to the bottom and may be removed. The material is 
usually submitted to a systematic treatment with water, in such 
a manner that the pure water first comes in contact with the 
nearly exhausted substance, and then with the less exhausted in 
another tank, and so on until it reaches the last tank containing 
the fresh material. Such a series of tanks is known as a battery. 
The term extraction is generally used when solvents other than 
water are employed. It is possible to extract several substances 
from the original raw material by the successive use of several 
solvents such as water, alcohol, ether, and naphtha. 

CRYSTALLIZATION. Crystals are geometric solids which may 
form by the separation of a compound from its concentrated 



16 ELEMENTS OF INDUSTRIAL CHEMISTRY 

solution. The solubility of most substances increases as the 
temperature of the solvent, usually water, is raised. A limit 
may be reached, however, for every temperature when no more 
will dissolve, and the solution is said to be saturated. If the 
temperature be now decreased, crystals of the substance will 
separate; and these crystals, though formed in an impure mother 
liquor, may be quite pure. By evaporation or concentration of 
the mother liquor more crj^stals will result, which, however, will 
be less pure than the first crop. Thus this operation may be 
continued until the impurities accumulating in the liquor become 
so great that the crystals will enclose a large amount of foreign 
matter. This difficulty can be prevented to a certain extent by 
stirring the solution while crystallization takes place; this causes 
the separation of very small crystals, or crystal meal, which can 
then be washed so as to remove the adherent impurities. This 
process is usually spoken of as " Granulation." 

Fractional Crystallization. Crystals may be further 
purified by several successive recrystallizations. This is a method 
used for the separation of substances when mixed in a solution; 
isomorphous substances, that is, those crystallizing in the same 
system cannot, however, be separated in this manner. The only 
way to proceed in such a case is to so react upon the solution as 
to change the chemical composition of one of the substances in 
such a manner that separation by crystallization becomes pos- 
sible. As an instance of this may be mentioned the preparation 
of pure copper sulphate from a mixed solution of copper and fer- 
rous sulphates. When blue vitriol is made from copper pyrites 
it is usually accompanied by more or less green vitriol. From this 
mixed solution only crystals of copper sulphate mixed with iron 
sulphate can be obtained, these salts being isomorphous. By 
oxidizing the ferrous to the ferric sulphate this may be avoided 
and pure copper sulphate prepared. 

CALCINATION. In the process of calcination substances 
are submitted to the action of high heat, but not, however, to the 
point of fusion. Material may be calcined: to drive off moisture, 
to drive off some volatile constituent or cause a chemical action 
such as oxidation or reduction. The terms roasting, firing, glowing, 
or burning are sometimes used in place of calcination. The 
process is usually carried on in furnaces, of which there are three 
common types — reverberatory, muffle, and kiln. 

REVERBERATORY FURNACE. In the reverberatory or open 
roaster the material to be heated is exposed to the direct action 



GENERAL PROCESSES 



17 



of the fire gases. It consists essentially of an arched chamber 
built of brick and heated from a grate placed at one end, while 
the products of combustion and reaction are removed by a chimney 
at the other end. The material is placed upon the bed of the 
furnace, the fire gases pass over it and are deflected by the arched 
form of the roof of the furnace so as to come more directly in 
contact with the charge. The insides of such furnaces are lined 
with firebricks, while the outsides are built of common bricks. 

If an oxidizing reaction is desired, that is, if the fire gases are 
to contain an excess of oxygen, such condition may be produced 
by setting the fire bars widely apart and feeding the fuel in thin 
layers at a time. Should a reducing action be desired, the fire 
bars must be placed closer together and the fuel charged in thick 
layers. 

MUFFLE FURNACE. The muffle furnace, closed or blind 
roaster is built in such a manner that the fire gases do not come 
in contact with the substances to be calcined. It generally con- 
sists of a muffle of firebrick with the flues so arranged that the 
hot gases pass underneath the bed of the muffle and are then con- 
ducted over the top, back to some point near the grate, where 
they are discharged into the chimney. A pipe is sometimes 
fitted to the top of the muffle in order to discharge any gases 
which may be formed during calcination. 

REVOLVING FURNACE. It is frequently necessary to stir 
the material during calcination, which would entail much heavy 
labor if done by hand ; 
to obviate this, me- 
chanical means have 
been devised, the most 
important of which is 
the revolver or revolv- 
ing furnace. It consists 
of a drum or cylinder 
of iron or steel, Fig. 20, 
lined with refractory 
material and open at T 
both ends. The drum, 
which may or may not 

be inclined, revolves slowly about its longitudinal axis, while the 
highly heated gases, from the grate situated at one end, pass 
through it. The hot gases leaving any of these furnaces may be 
economically used for drying or evaporating. 




W^W 



18 ELEMENTS OF INDUSTRIAL CHEMISTRY 

KILNS. Kilns or shaft furnaces may be periodic or continuous, 
and are very largely used in the burning or calcination of lime- 
stone. In periodic kilns the calcined charge is allowed to cool, 
then withdrawn and the kiln recharged with fresh material. In 
the continuous form the calcined material is drawn from the 
bottom at the same time that a fresh charge enters the top, the 
operation being a continuous one. 

EVAPORATION. By evaporation is understood the conver- 
sion of a liquid into a vapor for the purpose of recovering any 
solid matter which may be dissolved in it. In most instances 
the liquid to be evaporated is water. Other liquids would be 
recovered, and the process termed distillation. 

Spontaneous Evaporation. This method is usually 

conducted in the open air by exposing the liquid in large shallow 
pans. The time required depends entirely upon atmospheric con- 
ditions, the best results being obtained on a windy day in hot, 
dry weather. 

Evaporation by Direct Heat. By this method the 
flames or hot gases may play directly on the bottom of the con- 
taining vessel, or they may be made to pass over the surface of 
the liquid. In the former case the usual method is to employ 
large shallow pans which are so arranged as to be heated from the 
waste gases from other operations. In the latter mode of evapo- 
ration, the flue dust and ashes are very apt to fall into the pan, 
thus causing the product to become impure. This method is 
used, however, to some extent where the purity of the product 
is not essential. 

Evaporation by Indirect Heat. The use of steam is 
very largely employed for the reason that it is convenient to 
handle, and there is no danger of injury to the product by over- 
heating. The simplest means of utilizing this method of heating 
is to circulate the steam through coils of pipe arranged inside the 
vessel. This method is especially adapted to the heating of 
liquids contained in wooden tanks. The temperature to which 
the liquid may be raised depends wholly upon the steam pres- 
sure, which may be regulated to suit the conditions required. 

STEAM- JACKETED KETTLES. The most convenient method 
of applying steam is by means of the steam -jacketed kettle, a 
cut of which is shown in Fig. 21. In conducting an evaporation 
the valve to drain pipe is opened in order to allow the first con- 
densations to escape, and to prevent bumping. The exhaust 
valve is now opened, the inlet valve given a half turn, and then 




GENERAL PROCESSES 19 

slowly opened until a good supply of dry steam issues from the 
drip. The drip is finally closed and the inlet of steam so regu- 
lated as to secure the proper heat for evaporation. The kettles 
in common use are constructed of copper or cast iron, the jacket 
usually covering one-half of the 
kettle. For purposes where copper 
or iron will not resist the action 
of acids or other chemicals, it is 
customary to employ an enamel- 
lined kettle, which enamel consists 
of an easily fusible glass. In 
many operations it is necessary to 
stir the liquid being evaporated, 
to accomplish which the kettle is 
generally equipped with an agitator 
provided with paddles of various 
shapes. Fig. 21. 

Recently several forms of acid- 
proof iron have been brought on the market, Vessels constructed 
of these materials appear to be giving entire satisfaction. 

Evaporation under Reduced Pressure. There are many 
forms of apparatus employed for evaporating under reduced pres- 
sure, yet they all depend upon the same principle. 

VACUUM PAN. The necessary equipment for this installa- 
tion is a vacuum pan, condenser, receiver and pump. The pan 
is usually a globular copper or iron vessel, which is provided with 
a manhole, a discharge opening at the bottom, a thermometer, 
a vacuum gauge, peep holes, test cocks, liquor gauge and catch- 
all. In most of the larger pans the heating is accomplished by 
means of steam coils placed in the bottom of the pan, while the 
smaller sizes have a steam jacket. At the top of the pan is a 
dome or large pipe connected with the " catch-all," the purpose 
of which is to retain any liquid that may be carried along mechan- 
ically by the steam. A small pipe at the bottom of the catch-all 
returns the water to the pan, while a larger one is connected to 
the condenser. The condenser is a tin-lined copper coil sur- 
rounded by running water. Joined to the condenser is the 
receiver, which, like the pan, is provided with a liquor gauge. 
Attached to the receiver is the pump which in such an apparatus 
would be one working on the dry system. In many cases, how- 
ever, it is not necessary to collect the liquid passing off, so 
that it is then possible to dispense with the condenser and employ 



20 ELEMENTS OF INDUSTRIAL CHEMISTRY 

a vacuum pump which works on the wet system. A wet-system 
pump is so constructed as to take care of all condensations with- 
out the aid of an extra condenser. 

Multiple-effect System. The most efficient method 
of evaporation is that secured by means of the multiple-effect 
system. The apparatus usually consists of three or four vacuum 
pans, so arranged that the steam from the first pan passes through 
the coils or jacket of the next in line, and the steam generated in 
the second serves to heat the liquid in the third. The vacuum 
maintained in each of the pans increases as it approaches the 
pump for the reason that the condensations play quite an impor- 
tant part in producing reduced pressure. Thus it is that the pan 
having the highest temperature has the least vacuum, and that 
having the greatest vacuum has the least temperature. As a 
rule only three pans are employed, being known as triple effect, 
although sometimes four are used, when they are known as quad- 
ruple effect. 

YARYAN EVAPORATOR. This apparatus consists of a large 
number of small tubes joined together in groups of six, each group 
of which is a unit. The tubes of each set are joined in such a 
manner as to form a continuous coil, each end of which is free, 
the whole being enclosed in an outside shell of boiler plate. 

In the operation of this apparatus the steam is allowed to 
enter the cylindrical chamber surrounding the series of tubes. 
Either exhaust or pressure steam may be used, as desired. The 
solution to be concentrated is passed into the coils under pressure 
and being highly heated is converted into a mass of foam, which 
finally escapes from the last tube of the coil into the separator. 
Here it is discharged with considerable force against baffle plates, 
thus separating the liquid from the steam. The liquid collecting 
in the separator of the first effect is forced into the coil of the 
second effect, while the steam produced in the first effect is con- 
ducted into the chamber surrounding the tubes of the second 
effect, where its heat is utilized for further evaporation of the 
solution; thus the operation is repeated throughout the entire 
system. The steam from the final effect is passed into a con- 
denser, which in its turn is connected to a vacuum pump, 
thus producing a high vacuum in the separating chamber and 
coils. Owing to the reduction in the boiling-point of the liquid 
there is a condensation of the steam as it strikes the cooler pipes, 
thereby producing a less perfect vacuum in the preceding effect. 
Thus we have a gradual reduction of pressure and consequent 



GENERAL PEOCESSES 



21 



lowering of the boiling-point from the time the liquid enters the 
first effect until it is discharged from the last. The condensed 
steam, entrainments, from the chambers surrounding the coils, 
together with that from the condensers, is collected in many 
factories, and may be employed as feed-water for boilers or for 
other purposes. The ordinary form of vacuum pan will evaporate 
from eight to ten pounds of water per pound of coal, while it is 
claimed that the triple-effect Yaryan will evaporate from 23 to 
25 lbs., and the quadruple effect 30 lbs. 

LlLLIE EVAPORATOR. 1 The mode of operation which dis- 
tinguishes the " Lillie " from other forms of apparatus is that 
the results obtained are due to film evaporation; that is to say, 
the liquid flows over the heated tubes rather than through them, 
thus exposing a very large surface for evaporation. In the older 
forms of multiple-effect apparatus some difficulty was encountered 
from liquids which deposit heavy incrustations on the heating 
surfaces. This difficulty, how- 
ever, has been overcome in the 
new model. The new feature, 
which corrects this condition, 
is the reversal at will of the 
direction of the course of the 
vapors or heat through the 
multiple effect, making there- 
by, what before the reversal 
was the hottest effect the 
coolest, and what was the 
coolest the hottest. Fig. 22 
shows a vertical longitudinal 
section through the body cf 
the evaporator. The evap- 
orating tubes incline slightly 
downward to the steam end and open through the heavy tube 
plate partition in which they are firmly expanded and by which 
they are supported. The other ends of the tubes are closed save 
for a small air vent in each. They are not fastened or supported 
in any way, and the tubes are quite free to expand or contract 
independently of the shell of the effect. 

On the under side is a centrifugal circulating pump, located 
midway between the ends of the evaporator. The condensation 
from the steam in the tubes flows back into the steam end, and 

1 The Sugar Apparatus Manufacturing Co., Philadelphia, Pa. 




Fig. 22. 



22 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



thence through a steam trap into the end of the next cooler body, 
and finally to the atmosphere from the coolest body, in the case 
of the multiple effect. The solution delivered by the centrifugal 
pump is forced on to a perforated distributing plate, from which 
it flows over the tubes in a deluging shower. The circulation in 
this case is independent of ebbulition, and there being no depth 
of solution on the tubes the vapors have a free passage for escape. 
The method of heating and securing the reduced pressure is 
very similar to that of the Yaryan just described. 




Fig. 23. 



Another form of evaporator is shown in Fig. 23, which is self- 
explanatory. 

Distillation. This operation is. usually for the purpose of 
separating certain liquids from other liquids, or from solids, and 
may be considered as a special form of evaporation. In fact, 
evaporation and distillation are often carried on simultaneously. 
Many forms of distilling apparatus are in use, although they all 
have three points in common: (1) The still or vessel holding the 
liquid to be heated, (2) the condensers or cooling apparatus, and 
(3) the receiver or vessel in which the distilled liquid collects. 
Between the still and condenser is a spray catch, provided with 
baffle plates, to prevent any of the solution from being carried 
over mechanically by the vapor. By this means the liquid is 
returned to the still while the vapor passes along to the condenser. 



GENERAL PROCESSES 



23 



represents one 
The column or 




The apparatus shown is made of copper, the condenser worm 
being tin lined. 

COLUMN STILL. The illustration, Fig. 24 
of the types of column stills in common use. 
dephlegmator B is placed on top of 
the boiler A and is divided into 
chambers by means of plates, each 
of which has a dome or flat-covered 
opening, with an overflow pipe lead- 
ing to the chamber below. The 
vapor from the boiling liquid passes 
up through the opening, where it 
bubbles out through the liquid on 
each plate. The heavier liquid 
which is condensed here flows down 
through the overflow pipes and into 
the boiler. Between the column 
and the condenser E is a series of 
U-tubes surrounded by a water- 
bath, which may be kept at any 
temperature desired. As the mixed 
vapors pass through these tubes, 
the high-boiling portions are condensed and returned to the 
column, while the lightest or more volatile liquid only passes 
through the coil in the condenser E. 

COFFEY STILL. This form of apparatus, Fig. 25, consists 
of two towers: A known as the analyzer and B the rectifier. 
Free steam is forced into A through the pipe C, where it bubbles 
up through the liquid on the perforated plates D, D and out 
by the way of E into the rectifier B. The liquid to be dis- 
tilled is now pumped through the pipe F and the coil G, G, 
and is delivered into the analyzer by the pipe H. The liquid 
in this way becomes heated by the steam surrounding the coil 
and is delivered hot to the analyzer. The hot liquid as it falls 
on the perforated plates spreads out in a thin layer, and runs down 
to the next compartment through the overflow pipe J. The 
steam, as it passes up through the layers of liquid, heats it very 
hot and carries the volatile portion over into the rectifier. During 
the passage of the mixed vapors up the rectifier the steam becomes 
condensed by contact with the cold pipes, thus allowing the more 
volatile portion to pass out through the pipe K to the con- 
denser L. The water which collects in the bottom of the 



Fig. 24. 



24 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



rectifier is pumped to the top of the analyzer through the pipe 
M. From the bottom of the analyzer is a pipe N to act as a dis- 
charge for the spent liquor which has lost its volatile matter. 

CONVEYING SOLIDS. The man with a wheelbarrow is the sim- 
plest method of conveying solids, and is at the same time the 
least economical. A steel tray or wheelbarrow weighs from 60 
to 70 lbs., and will hold about 2 cu.ft. In a general way the 
laborer pushes the barrow through 200 ft. in a minute, and con- 
sumes about one and one-half minutes for loading and unloading. 
Larger barrows are made with two wheels, weighing from 200 to 
250 lbs., and having a capacity of 8 to 9 cu.ft. As a rule 
barrows are used on level surfaces only, and are made of various 




Fig. 25. 



shapes for special purposes. In some cases it is advisable 
to lay steel tracks and draw the cars by means of electric 
motors or small locomotives. The arrangements for dumping 
the cars vary to some extent, but of the ones in common use may 
be mentioned the V-shaped dump car, the gabled or saddle- 
bottom dump car and the hinged-end dump car. 

Cars which have to go up a steep incline may be hauled by 
a wire cable or run into an elevator. Endless chains or cables 
provided with catches to hold the car while it is being drawn up 
the incline are much used, especially for mining operations. An 
aerial cableway is often used where the country is rough and where 
it is necessary to cross a stream. The cable or wire rope is sus- 
pended from towers. The cable is usually endless, and along it 
are run carriages to which skips or buckets are attached. Material 



GENERAL PEOCESSES 25 

may also be moved by the use of the revolving locomotive crane 
with clamshell bucket or other form of container. A very effi- 
cient form of transportation is by means of the belt conveyor. 
These belts are usually made of rubber or cotton. The rubber 
belts (cotton duck coated with rubber) are especially designed 
for rough usage, while the cotton belts are more often employed 
for the carrying of boxes and packages. The belts, which may 
be flat or troughed, are run on rollers for support, the motion 
being imparted by a head pulley, and the slack taken up by the 
foot pulley. Different types of rollers are used according as the 
belt is flat or trough shaped. The capacity of such a conveyor 
depends upon the width of the belt and its speed, a troughed 
belt being able to carry two or three times as much load as a 
flat one. 

For the transportation of hot or very rough material bucket 
conveyors are generally employed. These buckets are carried 
on rollers and are joined together by a roller chain. Apron con- 
veyors are made by attaching light strips of wood or metal to link 
chains, thus forming a continuous belt much used for handling 
light packages. 

In drag or flight conveyors the material is pushed along, the 
simplest form being one in which the plain scraper is drawn by 
a central rope or wire. In the suspended draw conveyor the 
flights are attached to crossbars having wearing shoes at either 
end which slide on angle-iron tracks. In the roller flight con- 
veyor the shoes are replaced by rollers. 

The screw conveyor consists of a shaft around which metal 
flights are bolted to form an endless screw, this shaft rotating in 
a trough pushes the material along. 

When material is to be lifted any distance it is done by bucket 
elevators. The buckets are fastened to belting or link chains. 
A bucket shaped like the letter L is easily discharged, and is there- 
fore largely used for conveying pasty material; those shaped like 
the letter V have a larger capacity, but do not empty so readily 
as the L-shaped. The buckets may be made of steel, malleable 
iron or copper, according to the use to which they are to be put. 
They are also sometimes perforated to allow the material to 
drain, while others have saw edges, as those used for lifting tan- 
bark and such material. The belt to which the buckets are 
attached passes over two pulleys and the material is discharged 
by centrifugal force as it goes over the top one. For conveying 
barrels and boxes special elevators have been designed. 



26 ELEMENTS OF INDUSTRIAL CHEMISTRY 

CONVEYING LIQUIDS. The simplest problem which presents 
itself is the conveying of a liquid from a higher to a lower level, 
in this case gravity is the motive force; that is, the liquid is made 
to flow by means of a head. Liquids are usually conveyed in 
pipes which may be made of a variety of materials. For water, 
galvanized, or cast iron, lead, copper, tin, and alloys as well as 
ebonite are used. Earthenware and cement pipe are used exten- 
sively for waste material. Glazed pipe or vitrified tile find appli- 
cation for acid liquids; they are rather fragile, however, and should 
not be exposed to over 20 lbs. pressure to the square inch. 
Wooden pipes which are made of staves bound together with steel 
bands are much used for beer, vinegar, organic acids and dilute 
mineral acids. Lead pipe is very valuable in chemical industry, 
as it resists corrosion, but is not satisfactory when exposed to heat 
or pressure; for this reason iron pipes which are lead lined are 
much employed. Tin pipes are sometimes used in breweries, 
and for conveying distilled water, carbonated water, vinegar and 
wine; but owing to their expense tin-lined copper or iron pipes 
are more generally employed. Copper and brass pipes find 
extensive application, especially for conveying and use in the 
manufacture of dye-wood extracts and tanning materials. Wrought 
iron, either plain or galvanized, is used for the distribution of 
water, while cast-iron pipes are employed for conveying concen- 
trated acids. 

Elevating LIQUIDS. The most common method of lifting 
liquids is by means of pumps, which may be driven by steam, 
electricity, water, belt or gear. The pressure secured in a plunger 
pump is due to the force of a piston, while in a centrifugal, the 
pressure is obtained through a rotary motion imparted by means 
of revolving fans. The pulsometer and hydraulic ram are used 
to a limited extent. 

To withstand the action of acid and alkaline solutions, pumps 
are made of various materials; but for the elevation of more 
corrosive liquids the acid egg is generally used. Acid eggs are 
usually made of acid-proof cast iron and heavy enough to with- 
stand the necessary pressure; they are also sometimes made of 
earthenware. To operate, it is allowed to fill with the liquid, 
the ingress closed, then by the admission of compressed air the 
liquid is forced through a tube. The Harris system of elevating 
liquids by compressed air consists of two cylinders, opening into 
common fill and discharge pipes, the cylinders being filled by 
suction and discharged by pressure. 



GENERAL PROCESSES 27 

Where a liquid is to be transferred from a higher to a lower 
level the siphon is the simplest and most economical appliance 
which can be used. The simplest method to start the flow is 
to fill both limbs with the solution, and plunge the short arm 
into the liquid contained in the upper vessel. A very convenient 
form of siphon can also be arranged by having a swivel pipe 
attached to the bottom of the tank, and lower it to the proper 
level by means of a chain. 

Liquids are sometimes raised or conveyed by means of injec- 
tors which are usually operated by steam, and whose efficiency 
depends upon the principle of the difference in velocity of a jet 
of steam issuing from an orifice and that of a jet of water. The 
solutions raised by an injector become heated and diluted by the 
condensed steam. 

CONVEYING GASES. Gases, if valuable for manufacturing 
purposes as well as those which are of no use have to be conveyed 
from one part of the plant to another, or entirely removed, as the 
case may be. The pipes used for this purpose may be of sheet 
iron, galvanized iron, cast iron, or wrought iron, as well as flues 
of brick, concrete, and lead-lined wooden ones. Gas blowers and 
exhausters are made either to overcome a low counter-pressure 
or rarefaction such as blowers and ventilators; or to overcome 
high counter-pressure, or exhaust against a high rarefaction. 
These go under the name of compressors and exhausters. Fan 
blowers consist of a number of blades fixed on a rapidly revolving 
shaft; they are only used where the counter-pressure is very 
slight. In pressure blowers the width of the blades are parallel 
with the shaft and enclosed in a casing, usually of metal. The 
higher the speed at which the blades revolve the greater the 
pressure. 

Chimneys are often used to carry off noxious gases as well as 
to create a draft and promote combustion of fuel. For a good 
draft height is especially desirable, while for the removal of 
noxious gases size is perhaps the more important. Forced draft 
may be produced by blowing air through the flues or by exhaust- 
ing the gases formed during combustion. That chimneys deliver 
noxious gases at a sufficient height to prevent deleterious action 
on vegetable and animal life should also be taken into consider- 
ation. 

REFRIGERATION. The principle involved in all refrigerating 
machines is the absorption of heat by the evaporation of a volatile 
liquid. The substances in most common use are liquefied 



28 ELEMENTS OF INDUSTRIAL CHEMISTRY 

ammonia, sulphur dioxide, and carbon dioxide. The one most 
commonly employed, however, is ammonia, and it is used both in 
the compression and the absorption systems. 

Compression System. The gas being heavily compressed is 
liquefied by passing it through coils over which cold water is 
allowed to flow ; the liquid is then passed through a small opening 
into a large coil of pipe. The expansion of the ammonia from 
a liquid, to a gaseous state causes the absorption of much heat, 
with the result that the temperature falls below the freezing- 
point of water. The gases formed in the expansion pipes are 
rapidly exhausted by means of a pump and returned to the com- 
pressor, where the cycle is repeated, it being necessary only to 
supply sufficient ammonia to replace that lost by leakage. 

For the manufacture of artificial ice the expansion coils are 
surrounded with a strong brine or calcium-chloride solution, into 
which galvanized-iron boxes filled with water are immersed. 
When used for cold storage it is desirable to increase the cool- 
ing surface of the expansion coils. To do this cast-iron disks are 
placed at frequent intervals on the pipe perpendicular to its line 
of direction and the pipes suspended from the ceiling of the 
room. 

Absorption System. The York absorption refrigerating ma- 
chine consists of a generator, analyzer, dehydrator, ammonia 
condenser, ammonia receiver, exchanger, weak aqua cooler, 
absorber, strong aqua tank, aqua ammonia pump and pressure 
gauges. In operating this machine steam is admitted to the 
generator coils, thus heating the aqua ammonia to boiling. The 
liberated gas parses upward through the analyzer, which is 
mounted on top of the generator, where some of the water still 
left in suspension in the gas is removed by coming in direct con- 
tact with the incoming strong aqua ammonia from the absorber. 

On leaving the analyzer the gas enters the top of the dehydra- 
tor, where the remaining water is condensed. The now anhydrous 
gas enters the ammonia condenser, where it is liquefied, and drawn 
into the anhydrous liquid ammonia receiver. From this receiver 
it is admitted to the evaporating coils in which the refrigerating 
effect is produced. The expanded gas from the evaporating coils 
then enters the absorber, where it comes in contact with weak 
aqua ammonia, thus producing a solution of strong aqua ammonia. 
The strong aqua ammonia overflows from the absorber into a 
strong aqua tank; the aqua ammonia pump, taking its suction 
from this tank, discharges the strong aqua ammonia into the 



GENERAL PROCESSES 29 

exchanger at the bottom of the shell. In passing through the 
exchanger the liquid becomes heated to within 35 to 40° F. of 
the temperature of the generator by the weak aqua ammonia 
from the generator. On leaving the exchanger the strong aqua 
ammonia enters the top of the analyzer, where it is still further 
heated by passing over the baffle plates and coming in direct 
contact with the liberated gas from the generator. From the 
analyzer it enters the generator at very near the temperature 
due to the steam coils of the generator, is again boiled, and the 
cycle repeated. 



CHAPTER II 
WATER, ITS L USES AND PURIFICATION 

Composition of Natural Waters. All natural waters 
contain, dissolved or suspended in them, more or less of all 
materials with which they have come into contact. The;efore 
absolutely pure water cannot be obtained for industrial purposes, 
and the fitness of natural water for use in any given process 
depends on its content of other substances. 

In general waters from regions of old rocks like granite are 
low in mineral content; those from regions of limestone are hard; 
those from regions of alkali deposits are high in sodium and 
potassium; and those from swampy regions are highly colored.. 
Surface waters flowing through districts of easily disintegrated 
material like clay are muddy. The drainage from basins with 
low rainfall is more highly mineralized than that from more humid 
areas. Ground waters are usually higher in mineral content than 
surface waters in the same locality, though this superiority is 
somewhat counterbalanced by the fact that most ground waters 
are clear, while surface waters are frequently very muddy. 

USES OF WATER. In judging the value of a water from its 
analysis it is necessary to consider the supply both in relation to 
its intended use and in relation to other available supplies. 
Besides its domestic use, water is essential in steam making, 
paper making, starch manufacture, and many other industrial 
processes. For each of these applications the amounts of certain 
ingredients in the water determine its value and assist in its 
classification. For example, considerable iron in a water may be 
harmful in one process and harmless in another. The value of 
a water for another process may be directly measurable by the 
amount of suspended matter, the amount of dissolved matter 
not being significant. It is obvious that the chemical composi- 
tion of other available supplies should be taken into consideration, 
because the best water that can be obtained at reasonable expense 
should be used. Therefore, the best practice is to consider the 

30 



WATER, ITS USES AND PURIFICATION 31 

quality of the water in relation both to its application and to 
other local supplies. 

WATER FOR BOILER USE. The chief industrial use of water 
is for steam making, and its value for that purpose depends pri- 
marily on the amount and the chemical character of the mineral 
matter dissolved and suspended in it. The troubles in boiler- 
room practice caused by the mineral constituents of natural waters 
are scale formation, corrosion, and foaming. 

FORMATION OF SCALE. Formation of scale is the deposition 
of mineral matter within the boiler shell, and the deposit is called 
incrustation, sediment, or sludge according to its texture and its 
position. When water is heated under pressure and concentrated 
by evaporation as in a boiler, certain substances are thrown out 
of solution and solidify on the flues and crown sheets or within 
the tubes. These deposits increase fuel consumption because 
they are poor conductors of heat, and they also increase cost of 
boiler repair and attendance because they have to be removed.' 
If the amount of scale is great or if it is allowed to accumulate, 
the boiler capacity is decreased and disastrous explosions are 
likely to occur. Formation of scale is the most common boiler 
trouble, probably one-fifth of the steam generators in this country 
being found defective on that account. 

The scale of incrustation consists of the substances that are 
insoluble in the feed-water or become so within the boiler under 
conditions of ordinary operation. It includes practically all the 
suspended matter; the silica, probably precipitated as the oxide; 
the iron and aluminium, appearing in the scale as oxides or hy- 
drated oxides; the calcium, precipitated in the form of carbonate 
and sulphate; and the magnesium, found in the deposits prin- 
cipally as the oxide but partly as the carbonate. The scale con- 
stituted by these substances is, therefore, a mixture of compounds, 
which varies in amount, density, hardness, and composition with 
different conditions of water supply, steam pressure, type of boiler, 
and other circumstances. Calcium and magnesium are the prin- 
cipal basic substances in the scale, over 90 per cent of which 
usually is calcium, magnesium, carbonates, and sulphates. If 
much organic matter is present part of it is precipitated with the 
mineral scale, as the organic matter is decomposed by heat or by 
reaction with other substances. If magnesium and sulphates 
are comparatively low or if suspended matter is comparatively 
high, the scale is soft and bulky and may be in the form of 
sludge that can be blown or washed from the boiler. On the 



32 ELEMENTS OF INDUSTRIAL CHEMISTRY 

other hand a clear water relatively high in magnesium and sul- 
phates may produce a hard, compact scale that is nearly as dense 
as porcelain, clings to the tubes, and offers great resistance to the 
transmission of heat. Therefore the value of a water for boiler 
use depends not only on the quantity of scale produced by it but 
also on the physical structure of the scale. 

CORROSION. Corrosion, or " pitting," is caused chiefly by 
the solvent action of acids on the iron of the boiler. Free acids 
capable of dissolving iron occur in some natural waters, especially 
in the drainage from coal mines, which usually contains free 
sulphuric acid, and also in some factory wastes draining into 
streams. Many ground waters contain free hydrogen sulphide, 
a gas that readily attacks boilers; and dissolved oxygen and free 
carbon dioxide also bring about corrosion. Organic matter is 
probably a source of acids, for it is well known that waters high 
in organic matter and low in calcium and magnesium are corrosive, 
though the exact nature and action of the organic bodies are not 
understood. Acids freed in the boiler by the deposition of iron, 
aluminium, and magnesium as hydrates that are later partly or 
completely converted into oxides are the chief cause of corrosive 
action, and magnesium is the most important of these as it is the 
most abundant. According to the chemical composition of the 
water the acid radicles that were in equilibrium with these beses 
may do one or all of three things: they may pass into equilibrium 
with other bases, displacing equivalent proportions of carbonates 
and bicarbonates, or they may decompose carbonates that have 
been precipitated as scale, or they may combine with the iron of 
the boiler, thus causing corrosion. The certainty of these reac- 
tions can be expressed, even with the most complete analyses, 
only as a probability. If acid thus freed exceeds the amount 
required to decompose the carbonate and bicarbonate radicles, 
the iron of the boiler is attacked, and pits or tuberculations of 
the interior surface, leaks, particularly around rivets, and con- 
sequent deterioration of the boiler result. 

FOAMING. Foaming is the formation of masses of bubbles on 
the surface of the water in the boiler and in the steam space 
above the water, and it is intimately connected with "priming," 
which is the passage from the boiler of steam mixed with water. 
Foaming results when anything prevents the free escape of steam 
from the water, and the principal cause of it is usually believed to 
be an excess of dissolved matter that increases the surface tension 
of the liquid and thereby reduces the readiness with which the 



WATEE, ITS USES AND PURIFICATION 33 

steam bubbles break. Consequently, as sodium and potassium 
remain dissolved in the boiler water while the greater portion of 
the other bases is precipitated, the foaming tendency is commonly 
measured by the degree of concentration of the alkaline salts in 
solution, because this figure, in connection with the type of boiler, 
determines to a great extent the length of time that a boiler may 
run without danger of foaming. It is a fact that the worst 
foaming waters in railroad practice are encountered in arid and 
semiarid regions of the Southwest, where the quantity of dissolved 
alkali is greatest. However, it is well known that suspended 
matter can cause foaming, for certain surface waters that when 
clear do not foam, but deposit a moderate amount of scale foam 
badly whenever they carry a great quantity of mud. Greth 
states that the cause of foaming is among the following factors: 
the condition of the boiler, the design of the boiler, the size and 
shape of the water space, the steam pipe, irregular blowing off, 
introduction of oil into the feed water from the exhaust steam, 
neglect to change water periodically, irregularity of load, and 
improper firing and feeding. He concludes that it is not merely 
the presence of sodium salts in solution that causes foaming, but 
the presence of other substances which together with the sodium 
salts and operating conditions bring about foaming. A strong 
pure solution of sodium carbonate might not induce excessive 
foaming in a boiler, but suspended matter or precipitated sludge 
is invariably present under operating conditions, and the intro- 
duction of sodium carbonate would increase the suspended matter 
either by precipitating calcium and magnesium or by loosening 
previously deposited scale ; therefore, it is difficult under working 
conditions to distinguish between possible causes of the trouble. 
Experience has shown that the type of boiler, steam pressure, 
and other operating conditions accelerate or retard foaming to 
a great extent. 

Remedies for Boiler Troubles. The best remedy for 
troubles caused by substances in feed-waters is treatment of sup- 
plies before they enter boilers; this subject is considered under 
" Purification of Water." When such treatment cannot be given 
there are various ways of obviating trouble. Low-pressure, large- 
flue boilers are used in many stationary plants supplied with hard 
waters, and it is said that the scale formed in them is softer and 
more flocculent and can therefore be more readily removed than 
that in high-pressure boilers. Blowing off is about the only prac- 
tical means of preventing foaming, because this trouble is due 



34 ELEMENTS OF INDUSTRIAL CHEMISTRY 

principally to concentration of soluble salts in the residual water 
of the boilers. Accumulated sludge, or soft scale, can be removed 
by blowing, particularly in locomotive practice. In condensing 
systems much of the trouble due to mineral matter in the feed- 
water is obviated because the quantity of raw water supplied is 
proportionately small. Yet the problem is not completely solved 
in such systems because the incrusting or corrosive action is trans- 
ferred from the boiler to the condenser, which requires more or 
less cleaning and repairing in proportion to the undesirable quali- 
ties of the water supply. 

BOILER COMPOUNDS. Boiler compounds are widely used in 
regions where hard waters abound, but treatment within the 
boiler should be given only when it is impossible to purify the 
supply before it enters the boiler or when a relatively pure supply 
requires only minor correction. If previous purification is not 
practicable some feed-waters can be improved by judicious addi- 
tion of chemicals. Many substances, ranging from flour, oatmeal, 
and sliced potatoes to barium and chromium salts, have been 
recommended for such use, but only a few have proved to be 
really efficient. These substances have been classified according 
to their action within the boiler. Those that attack chemically 
the scaling and corroding constituents precipitate incrusting matter 
and neutralize acids. Soda ash, the commercial form of sodium 
carbonate, containing about 95 per cent Na2COs, is the most 
valuable substance of this character, because it is cheap and its 
use is attended with the least objectionable results. Tannin and 
tannin compounds are also used for the same purpose. The 
addition of limewater to the feed-water to prevent corrosion and 
to obviate foaming has been recommended, and it is probable 
that lime used with waters high in organic matter and very low 
in incrustants would improve them. Such practice increases the 
incrustants in proportion to the lime added, but prevents injury 
of the boiler by corrosion. Soda ash neutralizes free acids, pre- 
cipitates the incrusting ingredients as a softer, more flocculent 
material, which is more easily removed, and increases the foaming 
tendency of the water by increasing its content of dissolved 
matter. The proper amount of it to be used depends on the 
chemical composition of the water and the style of boiler. The 
second class of boiler compounds comprises those that act mechan- 
ically on the precipitated crystals of scale-making matter soon 
after they are formed, surrounding them and robbing them of 
their cement-like action. Glutinous, starchy, and oily sub- 



WATER, ITS USES AND PURIFICATION 



35 



stances belong to this class, but they are not now used to any 
considerable extent, because they thicken and foul the water 
more than they prevent the formation of hard scale. The third 
class comprises those that act mechanically, like those of the second 
class, and also partly dissolve deposited scale, thus loosening it 
and aiding in its ready removal. Kerosene is very effective, but 
graphite is believed to be still better. 

Many boiler compounds possessing or supposed to possess one 
or more of the functions ju?t described are on the market and 
are widely sold. Some are effective and some are positively 
injurious. Most of them depend for their chief action on soda 
ash, petroleum, or a vegetable extract, but all are costly compared 
with lime and soda ash. It can be readily understood that boiler 
compounds cannot in any manner reduce the total amount of 
scale but may increase it. Their only legitimate functions are 
to prevent deposition of hard scale and to remove accumulations 
of scale that have become attached to the boiler. It should 
always be borne in mind that a steam boiler is an expensive 
piece of apparatus and that boiler repairs and fuel are also expen- 
sive. It is far more economical to have the water supply analyzed 
and to treat it effectively by certain well-known chemicals in 
proper proportion, either within or without the boiler, than to 
experiment with compounds of unknown composition. 

NUMERICAL STANDARDS. The committee on water service 
of the American Railway Engineering and Maintenance of Way 
Association have offered a classification of waters in their raw 
state that may be employed for approximate purposes, but, as 
their report states, "it is difficult to define by analysis sharply 
the line between good and bad water for steam-making purposes." 

Approximate Classification of Waters for Boiler Use 



Incrusting and corroding 

constituents.* 

Parts per million. 


Classifica- 
tion. 


More than 


Not 
more than 


90 
200 
430 


90 

200 
430 
680 


Good 
Fair 
Poor 
Bad 



Foaming constituents. f 
Parts per million. 


Classifica- 
tion. 


More than 


Not 
more than 


150 
250 
400 


150 
250 
400 


Good 
Fair 
Bad 
Very bad "! 

i 



* Proc. Am. Rv. Eng. and Maintenance of Way Assoc, Vol. V, 1904, p. 595. 
t Idem, Vol. IX, 1908, p. 134. 



36 ELEMENTS OF INDUSTRIAL CHEMISTRY 

The question how hard a water may be used without treat- 
ment can be decided by comparing the cost of artificially soften- 
ing the water with the saving effected by the use of softened water. 

The benefits include: 

Saving in boiler cleaning. 

Saving in boiler repairs. 

Saving in fuel due to decrease in scale. 

Increased number of boilers in service. 

Decreased depreciation of boilers. 

Value of materials removed by softening plant. 

The cost of softening includes: 
Labor for operating softener. 
Power for operating softener. 
Softening chemicals. 
Interest on cost of installation. 
Depreciation of softening plant. 

Waste in changing boiler water due to increased foaming 
tendency of the water. 

In general it is economical to treat waters containing 250 
to 850 parts per million of incrustants, and those containing less 
than the lower amount if the scale contains much sulphates. 
As the incrusting solids may commonly be reduced to 80 or 90 
parts per million, the economy of treating boiler waters deserves 
careful consideration in regions of hard water. 

The amount of mineral matter that makes a water unfit for 
boiler use depends on the combined effect in boilers of the soften- 
ing reagent used with such waters and of the constituents not 
removed by softening. Sodium salts added to remove incrust- 
ants or to prevent corrosion increase the foaming tendency, and 
this increase may be great enough to render a water useless for 
steaming purposes. It is not of much benefit to soften a water 
containing more than 850 parts per million of non-incrusting ma- 
terial and much incrusting sulphates. Trouble from foaming 
in locomotive boilers begins at a concentration of about 1700 
parts per million of foaming constituents and a concentration of 
7000 parts is about the limit of safety for stationary boilers. 
Though waters containing as high as 1700 parts per million of 
foaming constituents have been used, it is usually more economical 
to incur considerable expense in replacing such supplies by better 
ones. 



WATER, ITS USES AND PURIFICATION 37 

Water for Industrial Use other than Boiler Pur- 
poses. The manufacture of many articles is affected by the 
ingredients of natural waters. The quality of water for boiler 
service has already been discussed; with reference to factories 
it need only be added that increase of boiler efficiency often 
justifies purification of poor water when increased value of the 
manufactured product alone may not be considered to do so. 
This observation applies particularly to paper, pulp and straw- 
board mills, laundries, and other establishments where large 
quantities of water are evaporated to furnish steam for drying, 
and to ice factories and similar plants where distilled water is 
produced. But besides its use for steam making, water plays 
a specific part in many manufacturing processes. In paper mills, 
strawboard mills, bleacheries, dyeworks, canning factories, 
pickle factories, creameries, slaughter houses, packing houses, 
nitroglycerin factories, distilleries, breweries, woolen mills, 
starch works, sugar works, tanneries, glue factories, soap fac- 
tories and chemical works water becomes a part of the product 
or is essential in its manufacture. As the principal function of 
water in most of these establishments is that of a cleansing 
agent or a vehicle for other substances, a supply free from color, 
odor, suspended matter, microscopic organisms, and especially 
bacteria of fecal origin, and fairly low in dissolved substances, 
especially iron, is generally satisfactory; but there are some 
exceptions. Water hygienically acceptable is necessary where 
it comes into contact with or forms part of food materials, as 
in the making of beverages, sugar, and dairy or meat products. 
As all these ideal conditions are encountered in few natural 
supplies, the manufacturer is confronted with the problems of 
ascertaining what degree of freedom from these substances 
is necessary to prevent injury to his machinery or to his output 
and whether the cost of obtaining such purity is counterbal- 
anced by decreased cost of production and increased value of 
product. Competitive business methods and increased facil- 
ities of transportation have standardized the values of manu- 
factured articles so thoroughly that makers are now obliged to 
scrutinize carefully every item of production costs in order to 
obtain reasonable profits. Therefore any appreciable saving 
effected by improvement of the water supply is one of the easiest 
sources of profit for the manufacturer. 

POTABLE WATER. Water that is used on food materials in 
any industrial operation should be potable; that is, should be pal- 



38 ELEMENTS OF INDUSTRIAL CHEMISTRY 

atable, est helically unobjectionable, and absolutely free from 
anything that might cause disease. Increased public attention 
to the quality of foods and beverages makes this standard essen- 
tial and it is an extremely short-sighted manufacturer that dis- 
regards it. Because of this and because employees in many 
establishments use the mill supply for drinking, it is not out of 
place to note the requisites of water as a beverage. 

To be entirely acceptable in this respect water should be free 
from suspended matter, color, odor, and taste, and fairly cool. 
It should be free from disease-bearing germs and poisonous 
chemicals; and it should be low in dissolved mineral ingredients. 
The nearer a water approaches these conditions the more satis- 
factory it is for general use. 

PHYSICAL QUALITIES. Suspended mineral matter clogs 
pipes, valves and faucets, and growths of microscopic plants 
suspended in water frequently cause bad odors and stains in 
clothes. Color is usually due to dissolved vegetable matter and 
is a cause of serious objection in a domestic supply only when it 
exceeds 20 or 30 parts per million. Some waters, especially 
those containing iron, develop a turbidity of 10 to 30 parts per 
million on exposure to the air, due to precipitation of dissolved 
matter, and such condition gives rise to an apparent though 
not a real color. Odors may be caused by various conditions. 
One like that of rotten eggs is due to free hydrogen sulphide. 
Growths of microscopic organisms in tanks and water mains often 
have unpleasant odors that make the water objectionable. Per- 
fectly acceptable drinking supplies are free from color, odor, taste, 
and turbidity. 

BACTERIOLOGICAL QUALITIES. Before a water is used for 
domestic purposes there should be reasonable certainty that it 
is free from disease-bearing organisms. Yet present bacteriolog- 
ical technique does not permit positive statement regarding the 
presence or absence of such organisms, and it is advisable, there- 
fore, to guard supplies against all chances of infection. The 
disease germs most commonly cariied by water are those of ty- 
phoid fever. The bacilli enter the supply from some spot infected 
by the discharges of a person sick with this disease and though 
the germs are comparatively short-lived in water, they persist 
in fecal deposits and retain their power of infection for remark- 
able lengths of time. Consequently wells should be so located 
that their waters are guarded against the entrance of filth of any 
kind either over the top or by infiltration, and pumps and piping 



WATER, ITS USES AND PURIFICATION 39 

in the S3 r stem should also be protected. Water from a carefully 
cased well over 20 or 30 feet deep is acceptable if the well is 
located after the exercise of reasonable judgment in regard to 
privies, cesspools, and other sources of pollution. Open dug 
wells and the pits constructed as reservoirs around the tops of 
many casings are exposed to fecal contamination from above 
or through cracks in poorly built sidewalls. Care should be 
taken that the casings of deep wells do not become leaky near 
the surface of the ground so as to allow pollution to enter. As a 
a matter of ordinary precaution the ground should be kept clean 
and water should not be allowed to become foul or stagnant near 
any well, no matter how deep it is. If shallow dug wells are 
necessary they should be constructed with water-tight casings 
extending down as far as practicable into the well and also a 
short distance above ground.- The floor, or curbing, should be 
water-tight, and pumps should be used in preference to buckets 
for raising the water. Every possible precaution should be 
taken to prevent feet scrapings and similar dirt from getting into 
the water by way of the top of the well. Underground water 
is not only less likely to become contaminated if protected from 
surface washings, air, and light, but it keeps better and is less 
likely to develop microscopic plants that give it an unpleasant 
taste. 

CHEMICAL QUALITIES. Amounts of dissolved substances 
permissible in a domestic supply depend much on their nature. 
No more than traces of barium, copper, zinc, or lead should 
be present because these substances are poisonous. The occur- 
rence of these elements in measurable amounts in ordinary waters 
is so rare that tests for them are not usually made. Any constit- 
uent present in sufficient amount to be clearly perceptible to the 
taste is objectionable. Water containing two parts per million 
of iron is unpalatable to many people, and even this small amount 
can cause trouble by discoloring washbowls and tubs and by 
producing rusty stains on clothes. Tea or coffee cannot be made 
satisfactorily with water containing much iron because a black, 
inky compound is formed. Four or five parts of hydrogen sul- 
phide are unpleasant to the taste, and this dissolved gas is objec- 
tionable also because it corrodes well strainers and other metal 
fittings. The amounts of silica and aluminium ordinarily present 
in well waters have no special significance in relation to domestic 
supply. Approximately 250 parts of chlorides make a water 
taste " salty," and less than that amount causes corrosion. 



40 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Calcium and magnesium are chiefly responsible for what is 
known as the hardness of water. This undesirable quality is 
indicated by increased soap consumption, as calcium and mag- 
nesium unite with soap, forming insoluble curdy compounds 
with no cleansing value and preventing the formation of a lather 
until these two basic radicles have been precipitated. The use 
of soda ash to " break " hard waters, or to precipitate the cal- 
cium and magnesium, is common and effects saving in the cost 
of soap. 

PURIFICATION OF WATER. Purification of water is prac- 
ticed on a large scale with one or more of three objects in view: 
first, to render the supply safe and unobjectionable for drinking 
purposes; second, to reduce the amount of the mineral ingre- 
dients injurious to boilers; third, to remove substances injurious 
to the machinery or to the manufactured product in industrial 
processes. The largest purification plants in this country have 
been constructed for the purpose of producing potable waters 
without special attention to other possible uses, and some waters 
need no further treatment before being suitable for steaming and 
for general industrial purposes. But many other waters are 
hard, and increased appreciation of the value of good water has 
resulted in demand for the removal of the hardening constit- 
uents also. 

Removal of bacteria, especially those causing disease, and 
removal of turbidity, odor, taste, and iron are the principal 
requirements in purification of a municipal supply, elimination 
of bacteria and suspended master being the most important. 
The common methods of effecting such purification are slow 
filtration through sand and rapid filtration after coagulation, 
both methods usually being combined with sedimentation. The 
first process is known as " slow sand " filtration and the second as 
" rapid sand " filtration. The efficiency of such filters is meas- 
ured primarily by the ratio between the number of bacteria in 
the applied water and the number in the effluent. This figure, 
stated in percentage of removal, should be as high as 98, and it 
often reaches 99.8 per cent with a carefully operated filter of either 
kind under normal conditions. 

Removal of scale-forming and neutralization of corrosive 
constituents are the chief aims in preparing water for steam mak- 
ing and three general methods are employed, namely, cold chem- 
ical precipitation followed by sedimentation, application of heat 
with or without chemicals, usually followed by rapid filtration, 



WATER, ITS USES AND PURIFICATION 41 

and distillation. The first process is carried on in cold-water 
softening plants and the second in feed-water heaters. The 
most efficient distillation is effected in multiple-effect evapo- 
rators. 

Besides the four common systems of purification that have 
been cited, several minor processes are used, sometimes alone 
but more frequently as adjuncts to filters or softeners. Surface 
waters are screened through wooden or iron grids or through 
revolving wire screens to remove sticks and leaves before other 
treatment. Coarse suspended matter can be removed by rapid 
filtration through ground quartz or similar material in units of 
convenient size provided with arrangements for washing the 
filtering medium similar to those used in mechanical filters. 
Very turbid river waters are first allowed to stand in sedimenta- 
tion basins in order to reduce the cost of operating the filters 
by preliminary removal of part of the suspended soils. Supplies 
undesirable only because of their iron content are aerated by 
being sprayed into the air or by being allowed to trickle over 
rocks or by other methods that cause evaporation of carbonic 
acid and absorption of oxygen, thus precipitating and oxidizing 
the iron in solution so that it can readily be removed by rapid 
filtration. Similar aeration is often employed for the purpose 
of evaporating and oxidizing dissolved gases that cause objection- 
able tastes and odors. 

Disinfection by ozone, copper sulphate, calcium hypochlorite, 
and other substances kills organisms that may cause disease or 
impart bad odors and tastes. Purification of this character 
must be done with substances that destroy the objectionable 
organisms without making the water poisonous to animals. 
Calcium hypochlorite, sodium hypochlorite, and chlorine gas 
are used to disinfect drinking water, and treatment with these 
substances is now widely practiced either as an adjunct to filtra- 
tion or as an emergency precaution where otherwise untreated 
supplies are believed to be contaminated. Disinfection by this 
method is not a substitute for purification by filtration, for it 
does not remove suspended matter nor appreciable amounts of 
color, organic matter, swampy tastes or odors, and it does not 
soften water. Natural purification of water is accomplished 
largely through biological processes in which the organic matter 
is oxidized by serving as food for bacteria, and objectionable 
organisms are destroyed by the production of conditions unfavor- 
able to their existence. Action of this kind takes place in reser- 



42 ELEMENTS OF INDUSTRIAL CHEMISTRY 

voirs and lakes, and it is also relied upon in many processes for 
the artificial purification of sewage. 

Slow Sand Filtration. Slow sand filtration consists in 
causing the water to pass downward through a layer of sand 
of such thickness and fineness that the requisite removal of sus- 
pended substances is accomplished. This filter is also called the 
continuous and the English filter. On the bottom of a water- 
tight basin commonly constructed of concrete, perforated tiles 
or pipes laid in the form of a grid are covered with a foot of 
gravel graded in size from 25 to 3 millimeters in diameter from 
bottom to top, and a layer of fine sand 3 to 4 ft. in depth is put 
over th& gravel, which serves only to support the sand. When 
water is applied on the surface it passes through the sand and the 
gravel, and flows away through the under-drain. The suspended 
solids, including bacteria, are removed by the sand, the action 
of which is rendered more efficient by the rapid formation of a 
mat of finely divided sediment on the surface. When this film 
has become so thick that filtration is unduly retarded, the water 
is allowed to subside below the surface and about half an inch of 
sand is removed, after which filtration is resumed. The sand 
thus taken off is washed to free it from the collected impurities, 
and it is replaced on the beds after they have been reduced by 
successive scrapings about a foot in thickness. As cleaning 
necessitates temporary withdrawal of filters from service they 
are divided into units of convenient size, usually half an acre 
each, so that the operation of the system may not be interrupted. 
Most modern filters are roofed and sodded, as this facilitates 
cleaning by preventing the formation of ice, permits work on the 
filter beds in all kinds of weather, inhibits algae growths, and 
prevents agitation of the water by wind and rain. 

RAPID SAND FILTRATION. The distinctive features of the 
rapid sand process are the coagulant and the high rate of filtra- 
tion. This type is also known as the American filter and it was 
formerly called the " mechanical " filter because of the con- 
trivances for washing the filtering medium. The raw water dur- 
ing its entrance into the sedimentation basin, which is smaller 
than that used with slow sand filters, is treated with a definite 
proportion of some coagulant, which forms by its decomposition 
a gelatinous precipitate that unites and incloses the suspended 
material, including the bacteria, and absorbs the organic color- 
ing mAter. This combined action destroys color and makes 
suspemted particles larger and therefore more readily removable. 



WATER, ITS TjSES AND PURIFICATION 43 

Aluminium sulphate, the coagulant most commonly used, is 
decomposed, aluminium hydrate is precipitated, and the sulphate 
radicle remains in solution, replacing an equivalent amount of 
the carbonate, bicarbonate, or hydroxyl radicle. The natural 
alkalinity of many waters is sufficient to effect this reaction. 
According to Hazen one part per million of ordinary aluminium 
sulphate should be allowed about 0.6 part of alkalinity expressed 
as CaC03 to insure complete decomposition. If the alkalinity 
is not sufficient, part of the aluminium sulphate remains in solu- 
tion and good coagulation does not take place. Therefore lime 
or soda ash is added if the alkalinity is too low. The proper 
amount of aluminium sulphate to be used is determined by the 
amounts of color, organic matter, and suspended matter and by 
the fineness of the suspended matter, and is best ascertained by 
direct experimentation with the water to be purified. It may vary 
from 12 or 15 parts per million for water with 10 parts of sus- 
pended matter and a color of 30 to 25 or 30 parts for a water with 
a turbidity of 400 and a color of 80. Ferrous sulphate is used 
instead of aluminium sulphate as a coagulant in some plants; 
lime must be added with it in order to bring about proper coagu- 
lation. 

The water, after having been mixed with the coagulant, is 
allowed to stand three or four hours in the sedimentation basin, 
where a large proportion of the suspended pai tides is deposited. 
It is then passed rapidly through beds of sand or ground stone 
to remove the rest of the suspended matter. Sand with an effect- 
ive size somewhat greater than that customary for continuous 
filters is used. Many filters now in use are built of wood or iron 
in cylindrical form 10 to 20 ft. in diameter, and some are designed 
so that filtration can be hastened by pressure. The sand, 30 to 
50 ins. deep, rests on a metallic floor containing perforations 
large enough to allow ready issue of the water but small enough 
to prevent passage of sand grains. When the filter has become 
clogged the flow of water is reversed, filtered water being forced 
upward through the sand to wash it and to remove the impurities, 
which pass over the top of the filter with the wasted water. A 
revolving rake with long prongs projecting downward into the 
sand mixes it during washing and prevents it from becoming 
graded into spots of coarse or fine particles. Fig. 26 is a dia- 
grammatic vertical section of a rapid sand filter with a mechanical 
agitator. When filtration is taking place raw water enters through 
pipe A into the cylindrical tank filled with sand B under which 



44 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



d 



^uv 



•J. 



Lk 



Fig. 26. 



are grids of collecting pipes with small nozzles C discharging 

through pipe D. When 
-nJ~| the sand is to be washed 
-^n pipe A is shut off and 
~~ |j water is forced upward 
from pipe D into the sand 
while the agitator E with 
rake-like teeth F is re- 
volved by power. The 
dirty water is decanted 
over the gutter G and 
escapes through waste- 
pipe H. 

Cold Water Soften- 
ing. The principal ob- 
jects of water softening are to remove the substances that cause 
incrustation in boilers, 
particularly calcium and "^^n 

magnesium, and to neu- 
tralize those that cause 
corrosion. Chemicals of 
known strength properly 
dissolved in water are 
added to the raw supply 
in such proportion as to 
precipitate all the dis- 
solved constituents that 
can be economically re- 
moved by such treatment. 
The water is then allowed 
to stand long enough to 
permit the precipitate to 
settle, after which the 
clear effluent is drawn off, ' 
or the partly clarified efflu- 
ent may be filtered, very 
rapidly through thin beds 
of coke, sponge, excelsior, 
wool, or similar material, 
in order to remove parti- 
cles that have not subsided 
in the tanks. The water softeners on the market differ from 




Fig. 27. 



WATER, ITS USES AND PURIFICATION 45 

each other chiefly in the precipitant, in the filtering medium 
if one is used, and in the mechanism regulating the incor- 
poration of the chemicals with the water. Installations may 
be of any size to suit consumption, and the process can be com- 
bined with mechanical filtration for purifying municipal water 
supplies, as in the municipal plant at New Orleans. Fig. 27 
is a diagrammatic representation of a cold-water softener. The 
raw water passes by pipe A into box B, whence it falls over 
wheel C, generating power for operation. It then flows into 
the top of cone E after being mixed with the softening chemicals 
at D. The mixture settles in E and F and is filtered through 
excelsior G and finally flows out by pipe H. The chemicals 
are dissolved in tank /, and the solution is raised by pump J" 
to tank K, where it is kept mixed by agitator L. The float M 
raises or lowers pipe N, thus keeping the supply of chemicals 
proportional to the supply of raw water. The sludge is let 
out at 0. 

Among the substances that have been proposed as precipi- 
tant s are sodium carbonate, silicate, hydrate, fluoride, and phos- 
phate, barium carbonate, oxide, and hydrate 3 and calcium oxide, 
but of these substances lime and soda ash are almost exclusively 
used on account of their excellent action and comparative cheap- 
ness. When soda ash and lime dissolved in water to form solu- 
tions of known strength are added to a water in proper pro- 
portion, free acids are neutralized, free carbon dioxide is removed, 
the bicarbonate radicle is decomposed, and iron, aluminium, and 
magnesium hydrates and calcium carbonate are precipitated. 
The four basic substances are removed to the extent of the solu- 
bility of these compounds in water, and the calcium added as 
lime is also precipitated; in other words the scale-forming in- 
gredients are removed. 

PERMUTIT. There has recently been brought on the market 
a product known as " Permutit," which is an artificial zeolite 
having the formula Al2O3-10SiO2-10Na 2 O. The valuable prop- 
erty of this substance is to exchange its sodium for the bases 
calcium and magnesium, which it does when brought in contact 
with solutions containing these elements. Therefore if a hard 
water is passed through a bed of permutit, the sodium of the 
permutit is replaced by the calcium and magnesium of the 
water forming a calcium-magnesium permutit, while the acid 
radicles formerly united to the calcium and magnesium in the 
water unite with the sodium. It will be seen by this that the 



46 ELEMENTS OF INDUSTRIAL CHEMISTRY 

hardness of the water is removed, although the amount of total 
solids will remain the same. 

When the sodium of the permutit has become exhausted by 
the replacement with magnesium and calcium it is treated with 
a salt solution which by mass action converts the exhausted 
permucit back to its original condition. This treatment can go 
on indefinitely. The method of handling is very simple in that 
all that is required is a number of tanks containing the per- 
mutit. The water runs through the bed thus formed and comes 
from the filter free from incrustatmg materials. 

FEED-WATER HEATING. Water heaters are designed pri- 
marily for the purpose of utilizing waste heat in stationary boiler 
plants by raising the temperature of the feed-water and thereby 
lessening the work of the boilers themselves, but they also effect 
some purification, and many heaters have been specially con- 
structed to take advantage of that effect. The heat is derived 
from exhaust steam or from flue gases, and the heaters utilizing 
steam are either open, that is, operated at atmospheric pressure, 
or closed and operated at or near boiler pressure. In accordance 
with these three conditions, which result in distinct purifying 
effects, feed-water heaters are classified as open or closed or 
economizers, the last being those using flue gases. In most open 
heaters, which are best adapted for removing large quantities of 
scale-forming material, the steam enters at the bottom and the 
water at the top, and intimate contact between the two is obtained 
by spraying the water or by allowing it to trickle over or to 
splash against plates. In this manner the water is quickly heated 
nearly to boiling temperature. Dissolved gases are expelled, the 
bicarbonate radicle is decomposed, and the iron, aluminium, part 
of the magnesium, and calcium equivalent to the carbonates 
after decomposition of the bicarbonates are precipitated as 
hydrates, oxides, and carbonates under varying conditions of 
temperature, pressure, and time. The precipitate agglomerates 
the particles of suspended matter and makes them more readily 
removable by sedimentation and filtration. The slowness with 
which the reactions take place and the presence of acid radicles 
other than carbonates to hold the bases in solution prevent com- 
plete removal of calcium and magnesium. The addition of soda 
ash in proper proportion, however, effects fairly complete precipita- 
tion of the alkaline earths, and apparatus for constant introduc- 
tion of this chemical in solution may be provided. After the 
precipitate has been formed the water passes through filters of 



WATER, ITS USES AND PURIFICATION 47 

burlap, excelsior, straw, hay, wool, coke, or similar material 
arranged in units that can readily be cleaned. Open heaters 
operated without a chemical precipitant remove substances that 
are soft and bulky and leave in the water the constituents that 
form hard scale ; scale from water treated in such heaters is there- 
fore not so great in amount, but is harder than that formed by 
the raw water. The open feed-water heater and receiver utilizes 
the exhaust and brings it into intimate contact with the 
raw water, not only softening the latter, but also heating it for 
boiler use. 

In closed heaters the water is passed through metal tubes 
surrounded by steam at high pressure or around pipes in which 
steam circulates, and manholes or other openings are provided 
for cleaning the scale from the tubes. As the water is heated 
under pressure some precipitation takes place, but closed heaters 
are not so efficient in this respect as open heaters, because they 
do not permit escape of the gases liberated from the water. This 
objection does not hold if treatment in a closed heater follows 
treatment in an open one from which the gases escape, and 
several systems accomplish very good purification by using a 
unit of each type in series. 

Economizers consist essentially of water tubes set in the flues 
leading from the furnaces. Facilities are provided for cleaning 
scale from the inside and soot from the outside of the tubes. 
As economizers are heated by flue gases, the water in the tubes 
can be heated under pressure to a much higher temperature than 
in open or closed heaters, and the boiler conditions described in 
the section on water for steam making are approximated. The 
precipitation of incrustants varies greatly with the normally 
fluctuating temperature of the flue gases. 

DISTILLATION. The natural waters in some regions are so 
strongly mineralized or so badly polluted as to be unfit for general 
industrial use even after being filtered or softened, and water 
practically free from all dissolved and suspended matter is neces- 
sary for some industrial processes. Under such conditions the 
water must be distilled. This process is carried on in some 
factories by condensing steam from ordinary boilers, but if large 
quantities are required the installation of multiple-effect stills 
is advisable, for by their use the cost of producing pure water 
is greatly reduced. The principle of distillation is too well known 
to require detail; multiple-effect stills are so designed that by 
proper adjustment of steam pressures and temperatures, the heat 



48 ELEMENTS OF INDUSTRIAL CHEMISTRY 

interchange between the purified and raw supplies is utilized to 
produce great efficiency. The best stills have attachments by 
which the noxious volatile substances and gases are eliminated. 
Distillation is the only commercial process by which supplies 
suitable for industrial use can be obtained from salt or strong 
alkali waters. 



CHAPTER III 

FUELS 

DEFINITION. A fuel is a substance whose combustion in 
atmospheric oxygen can be utilized as a source of heat energy for 
commercial or domestic purposes. They are most conveniently 
considered as* divided into three natural classes: solid, liquid, 
and gaseous. 

Elementary Constituents. The two elements which 

contribute most to the heating power of fuel are carbon and 
hydrogen. Though other elements, such as sulphur, contribute 
somewhat to the formation of heat, the two mentioned above 
are by far the most important. That portion of the oxygen 
which occurs in the fuel as a partial oxidation product of some 
compound constituent thereof causes a loss in the heating value, 
as its presence means that a certain amount of the oxidation and 
heat development have been accomplished outside the furnace. 
Sulphur in small amounts is usually found in fuels. In large 
amounts it is undesirable, as it has a corrosive action and renders 
the fuel unfit for metallurgical uses. Nitrogen is usually an 
inert constituent, escaping uncombined during combustion. 
Silicon and phosphorus are also found in fuels, the latter being 
undesirable in metallurgical work. Together with the last two 
there is usually a considerable amount of mineral matter which 
is left after combustion as ash, and usually a certain amount of 
water which occurs free in the fuel. Ash is undesirable, as it 
dilutes the combustible matter of the fuel, causes an additional 
expense for its removal, and may interfere seriously with the 
use of the fuel because of its low fusion point and the consequent 
tendency to form clinker. Water is a direct loss of heat, as it 
dilutes the fuel, requires a large amount of heat for its evaporation, 
and by escaping up the flue at the temperature of the escaping 
gases, carries away a certain amount of heat. 

Heat of Combustion. The heat of combustion of a 
substance is the number of calories produced by the complete 
oxidation of 1 gram of it. As applied to fuels, it is called the 

49 



50 ELEMENTS OF INDUSTRIAL CHEMISTRY 

calorific value or heating power of the fuel. The calorific value 
is one of the most important points to be decided in the purchase 
of a fuel. Having decided the character of fuel best adapted to 
the purpose for which the purchase is to be made, the remaining 
point of chief consideration is the calorific value, which is deter- 
mined by means of a calorimeter. Solids and non-volatile liquids 
are usually burned in a heavy steel bomb in an atmosphere of 
oxygen under a pressure of about 25 atmospheres. The cal- 
orimeter is immersed in water contained in a vessel protected 
by non-conducting material from temperature changes. The 
temperature of the water before and after the experiment, the 
amount of water and the water equivalent of the calorimeter 
being known, the total amount of heat liberated by the action is 
obtained. 

SOLID FUELS. Wood. Wood is composed principally of 
cellulose and ligno-cellulose in about equal quantities, together 
with gums, resins, a variable amount of water, and inorganic 
matter left as ash when the wood burns. Cellulose has the 
composition (CeHioOs)^ and is the principal constituent of the 
cell membranes of young plants. The formula above serves 
only to give the percentage of the constituents, the molecule 
being very complex. 

Ligno-cellulose is the substance with which the cellulose of 
young plants becomes incrusted as it grows old, and becomes 
woody fiber. It is not a carbohydrate, and little is known of its 
chemical nature. 

Wood. Wood has a low calorific value, varying from 3000 to 
3500 calories, and contains a considerable amount of moisture, the 
amount depending on the kind of wood, the season in which 
it is cut, and the extent it has been allowed to dry, being rarely 
less than 18 per cent. Wood is of little value as a fuel, but it is 
sometimes used on account of its cleanliness and small amount 
of ash formed. 

Peat. There is no doubt that peat represents a comparatively 
early stage in the transformation which vegetable matter under- 
goes when sufficiently protected to prevent its complete oxida- 
tion, as in many localities it is possible to observe the transition 
from the vegetable matter covering the ground to the underlying 
peat in various stages of formation. In the upper portions the 
vegetable matter is easily discernible, while at the bottom, most, 
if not all, visible signs of plant remains disappear. The forma- 
tion of peat occurs in bogs or swamps where sufficient vegetable 



FUELS 51 

matter accumulates to give rise to the formation. The deposit 
from each year's growth, such as mosses, grasses, leaves, branches 
and trunks of trees fall and are partially protected by the water 
from complete decomposition. The action of organisms and 
atmospheric oxygen transforms this material first into a loose 
brown substance, finally, with the aid of pressure from above, 
into a brown or black peat. 

Little is known of the chemical compounds composing peat. 
Some solvents and solutions of alkalies dissolve considerable 
amounts of organic matter of a complex character from peat, 
but the substances obtained from these solutions are probably 
impure. 

Peat has long been used as a fuel, and in northern and western 
Europe, and in Ireland (where peat bogs are said to cover one- 
tenth of the total area) it has been extensively used. Peat bogs 
are also widely distributed in this country and in Canada. 

The recent peats are usually brown in color and approach 
wood in chemical composition, containing less oxygen and hydro- 
gen and more carbon. The oldest peats are usually dark in color, 
and the percentage of carbon is greater than in recently formed 
peats. 

Peat has a higher calorific value than wood, varying from 3500 
to 5000 calories. As it is cut from the ground it contains a large 
amount of water, often as much as 90 per cent of its weight. 
If the blocks are left to dry under cover in the air this is greatly 
reduced. The difficulty of freeing it from this water is one of the 
drawbacks to its use. By application of pressure much of it 
can be expelled, but it still contains a considerable amount on 
account of its jelly-like character. A recent observation that 
this jelly-like character is destroyed by heating it to 150° C, after 
which the water can be expelled by pressure, may assist in the 
solution of this difficulty. 

Peat is frequently formed into briquettes, when it makes an 
excellent fuel for domestic uses, as it burns with a bright cheerful 
flame and without much smoke. 

Lignite. Lignite and brown coal are names applied to the sub- 
stances which represent the next stage to peat in the transforma- 
tion of vegetable matter into coal. The distinction of lignite 
from peat on the one side and bituminous coal on the other is 
not sharp, as the transition from one to the other is gradual. 
Chemically, lignite seems to be more closely related to peat than 
to bituminous coal and, as with peat, it is found that certain 



52 ELEMENTS OF INDUSTRIAL CHEMISTRY 

solvents and solutions of alkalies dissolve considerable organic 
matter of a complex character from lignites. The evidences 
of vegetable origin are not usually distinct in lignites, though 
when properly treated, microscopic examination is usually able 
to show the remains of plant structure. In general, lignite is 
denser, darker in color, and contains more carbon than peat. 
It contains about 35 per cent of water, and on air-drying this falls 
to about 15 per cent. Its calorific value varies from 4000 to 6500 
calories. The amount of ash varies greatly, but should not 
exceed 10 to 15 per cent. 

On account of the difficulties encountered in shipping and 
storing lignite, its formation into briquettes has been practiced 
to a considerable extent, especially in Germany. In this country 
the necessity for using such fuels has not been greatly felt, and 
the operation of briquetting such fuel is here in its beginning. 
This question will be mentioned later in connection with bitumi- 
nous coal. 

Bituminous Coal. The next stage in the formation of coal 
is represented by bituminous coal, by far the most important of 
all the classes of fuels. The division of bituminous coals from 
lignites is more sharply defined than that of lignites from peats, 
but still the transition is gradual. 

The origin of coal is swamp flora laid down when the growth 
of vegetable matter was far more luxuriant than now, and which 
in earlier geologic ages has passed through successive stages 
which are represented now by peat bogs and beds of lignite. 

The properties of bituminous coals differ widely. The 
amount of volatile matter varies from 15 to 50 per cent, the 
amount of ash from 2 to 20 per cent, but the most marked differ- 
ences are observed in the coal substance when heated. The dif- 
ferences are noticed in the characters of both the volatile matter 
and the residue or coke. Some, when heated, fuse together to 
a compact mass, and if heated sufficiently leave behind a firm, 
solid mass composed principally of carbon and the ash of the 
coal. Such coals are said to be coking coals. Non-coking coals 
do not fuse and the mass left behind when such coals are heated 
coheres only slightly or not at all. 

Coals are frequently changed, after mining, by the absorption 
of oxygen and the loss of some of their combustible constituents, 
and on long standing their heating power is materially changed, 
some even losing their coking power. Frequently, this absorp- 
tion of oxygen is so rapid and accompanied with the evolution 



FUELS 53 

of so much heat that when large amounts are stored in one pile 
the temperature gradually rises until spontaneous combustion 
ensues. 

To overcome some of these difficulties and to utilize those 
portions of the fuel which unavoidably go to waste around the 
mine, finely divided coal is frequently mixed with pitch or tar, 
and compressed while hot into molds. These briquettes are 
less bulky, less likely to deteriorate and to undergo spontaneous 
combustion, and can be fired more efficiently than the raw coal. 
Where it is necessary to keep large stores of coal on hand, these 
advantages are sufficient to justify the operation of briquetting. 
The practice of briquetting coal and lignite is more common in 
Germany than in this country. 

One of the chief objections to the burning of bituminous 
coals is the production of smoke during combustion. It is 
doubtful if this can be prevented by any means which involves 
the introduction of fresh coal directly into the fire. Mechanical 
stokers are designed to bring the fuel into the fire slowly, and at 
a regular rate. In this way the volatile matter is expelled gradu- 
ally and mixed with sufficient oxygen for its combustion, the 
result being that less smoke is produced, the fire kept in a more 
uniform condition than is possible by hand firing, and at the 
same time the fuel is consumed more efficiently. 

Anthracite. In composition the anthracite coals approx- 
imate the final stage in the carbonization of vegetable matter. 
On one side of the anthracite we have bituminous coals separated 
by the semi-anthracites, and on the other side the anthracites 
approach graphite. As indicated above, anthracites contain 
a large amount of fixed carbon as compared with their content 
of volatile matter. They are denser than bituminous coals, 
have a cnnchoidal fracture, and a high kindling temperature. 
Anthracite is used largely for metallurgical work, for the manu- 
facture of producer and water gases, and for domestic purposes, 
As it has little volatile matter, and burns with a non-luminous 
flame, it is well adapted to these purposes. 

Charcoal. Charcoal is made from wood by two methods. 
By the first, wood is converted into charcoal by what is called 
the charring process. This consists of piling the wood into large 
circular heaps, leaving horizontal flues near the bottom and a 
vertical flue at the center for the escape of the evolved gases and 
covering over the whole, except for these points of ventilation, 
with powdered charcoal, earth and turf. At the points of ventila- 



54 ELEMENTS OF INDUSTRIAL CHEMISTRY 

tion the wood burns, the area of the combustion depending on 
the drafts, and the heat produced by the burning at these points 
suffices to raise the temperature of the whole mass to the point 
where most of the volatile matter of the wood is expelled. When 
all the volatile matter has been driven off and the escaping gases 
cease to burn with a luminous flame, the draft holes are covered 
and the operation stopped. By this process air-dried wood 
yields about 25 per cent of charcoal, but all the volatile matter 
is lost. 

By the second method of preparing charcoal provision is made 
for the recovery of these by-products, which consist of combus- 
tible gases, wood alcohol, organic acids, acetone and tar. The 
operation consists in the destructive distillation of wood from 
closed vessels, the charcoal remaining in the retort. For the 
production of charcoal for certain purposes these retorts are heated 
by means of superheated steam. 

Charcoal is quite porous and brittle and retains the shape of 
the wood, though the pieces are only about three-fourths the 
size of that of the wood. It still contains traces of volatile matter 
from which it is impossible to free it, and the ash-forming con- 
stituents of the wood. It burns with little flame, contains little 
sulphur and phosphorus, a low amount of ash, and has been ex- 
tensively used in metallurgical work, especially for the produc- 
tion of the finer grades of iron and steel. Its calorific value 
is about 7000 calories. The porosity depends on the character 
of the wood used in preparing it, some giving a denser product 
than others. It possesses the peculiar property of condensing 
many gases before they reach their point of liquefaction, and of 
abstracting coloring matter from solutions. This power of 
absorbing materials is frequently utilized to purify solutions from 
tarry materials and coloring matter. Because of the great ten- 
dency of charcoal to hold back small amounts of other substances 
perfectly pure amorphous carbon is unknown. 

Coke. Coke is the residue left after the destructive dis- 
tillation of coal, and is composed principally of carbon and the 
ash-forming constituents of the coal from which it was formed. 

The production of coke was at first carried out in much the 
same way that charcoal is obtained from wood in charcoal kilns; 
the bee-hive oven of to-day, in which a large amount of the coke 
produced in this country is made, is a development of this method. 

Fig. 28 illustrates the bee-hive oven as used in this country. 
It is simply a dome-shaped enclosure built of firebrick, 12 ft. in 



FUELS 



55 



diameter, 7 ft. high, with an opening at the top for charging and 
for the escape of the products of combustion and volatile matter 
formed during the operation, and a door at the side through 
which the coke is withdrawn, usually by hand, at the end of the 
operation. This door is built up with firebricks during the 
process, except at its top above the level of the charge. In this 
way five or six tons of coal are coked at each charge, and the 
time required is from forty-eight to seventy-two hours, yielding 
from 60 to 65 per cent of coke. The operation is brought to an 
end by quenching the fire in the oven with a stream of water, 
after which the coke is withdrawn. These ovens are usually 




Fig. 28. 



built together in one or two rows, with a track on top to bring 
up the coal. 

As seen from the above description, the burning of a part of 
the coal furnishes the heat necessary for coking the remainder, 
and the volatile matter of the coal is either burned or turned 
into the air. 

Numerous forms of ovens have been designed to collect these 
products and use them. These so-called by-products consist of 
combustible gases, various organic compounds, compounds of 
nitrogen, including ammonia and tar. 

Figs. 29, 30, 31 and 32 are illustrations of three types of by- 
product coke ovens which are used considerably in this country 
and will serve to illustrate the operation. 



56 



ELEMENTS OF INDUSTRIAL CHEMISTRY 







SECTION THROUGH REGENERATOR ELEVATION TRANSVERSE SECTIONS' 

Fig. 29. 




FUELS 



57 



The Otto-Hoffmann type of oven is shown in transverse and 
longitudinal sections in Figs. 29 and 30. The coal is charged 
through d into the coking chambers D beneath. These are long, 
narrow retorts of firebrick construction placed side by side, 
usually in groups of fifty. In the walls separating the retorts 
are the vertical flues/, in which the gas evolved in coking previous 
charges is returned from the condensing house and burned to 
furnish the heat for coking the charge. The retorts are about 
33 ft. long, 6| ft. high, and 20 ins. wide, closed at each end by 
an iron door which is raised and lowered electrically, and during 
the coking process luted with fireclay. The air for the com- 
bustion of the gas passes through the checker work R, made of 




Fig. 31. 

refractory material, which, as we will see, is highly heated, the 
gas entering at the burner B. The burning gases pass along 
the horizontal flue Fi, and up each of the vertical flues / of one- 
half of the retort wall to the upper horizontal flue F 1 , then 
down the remaining vertical flues / of the second half of the 
wall to a similar horizontal flue F 2 , situated beneath the coking 
chamber D, then out through the second chamber or regener- 
ator R' filled with refractory checker work, where the heat of 
the escaping gases is abstracted by heating up the checker work 
to incandescence. After a certain length of time, when Z^'has 
been heated and R cooled, the currents of air and gas are reversed 
through the flues, the air entering through R' and the gas through 
another burner at the other end of the retort. The volatile 



58 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



products escape from D through the uptake pipes, provided with 
valves, and pass into the common main G at a high temperature, 
and are gradually cooled in the iron pipes, depositing some of the 
condensable portions, the remainder being subsequently removed 
in the condensing house. 

After the completion of the coking process, the charge is 
removed by a steam or electrically operated pusher, which pushes 




Fig. 32. 



the whole charge of the retort out on the opposite side, where it 
is rapidly cooled by a stream of water. 

The time required for coking a charge in this type of oven is 
about twenty-four hours, yielding about 70 per cent of coke. 

In the Semet-Solvay type of by-product oven, shown in Fig. 
31, the coking chamber D is somewhat similar to that of the Otto- 
Hoffmann oven above. They are built in sets of thirty or forty, 
are 35 ft. long, 1\ ft. high and 16J ins. wide. 

The coal is charged through d into the coking chamber D, the 
volatile products escaping through g into the common main G. 
The flues /, built in the walls of the ovens, are in this type five in 



FUELS 59 

number and arranged horizontally. The gas returned from the 
condensing house is delivered at the four burners B, and mixes 
with preheated air delivered from beneath the oven. The current 
of burning gases is from the top flue downward through each of 
the others, fresh gas burning at each of the burners during their 
downward course. The gases from the flues in each wall of the 
chamber pass into a single flue beneath D, thence into a series of 
channels with thin walls where the air passing to the burners is 
preheated, as stated above. The flue gases are subsequently 
passed through water-tube boilers, and their remaining heat used 
to generate steam for power purposes. A charge of from 7 to 9 
tons of coal can be coked in these ovens in about twenty-four 
hours. 

Fig. 32 shows a Kopper Coke Oven. In this type the 
chambers are heated by one generator, the gases passing along 
vertical flues. The chambers are 14 ft. long, 8 ft. high and 18J 
ft. wide. The chambers aie charged from the top of the larry 
with about four tons of coal at a time, the coke being pushed out 
by means of a ram. For each set of chambers a separate hydraulic 
main is provided. 

Coke is also obtained as a by-product in the manufacture cf 
coal gas, which will be mentioned later. But the coke obtained 
in this way is soft and unfit for metallurgical purposes, and is 
partly consumed in the producer used to heat the retorts, and for 
domestic purposes. 

During the coking process the coal fuses and the escape of the 
gases formed by the destructive distillation of the coal leaves the 
residue or coke full of cavities, the walls of which are quite hard. 
This cellular structure is very advantageous, as the coke to be of 
service for metallurgical work must be sufficiently strong to 
sustain the charge above without crushing, and at the same time 
must be porous. It has a silvery white luster, a metallic ring when 
struck and is infusible. It burns without smoke and has a calo- 
rific value of 7600 to 8100 calories. All of the ash of the coal 
and ordinarily about half of the sulphur remain in the coke, and it 
is frequently necessary to wash the coal to remove portions of 
these constituents in order to make a serviceable qualit}' of coke. 
The phosphorus of the coal is all found in the coke. Besides 
these, there is a considerable amount of nitrogen and water, and 
small amounts of hydrogen and oxygen which cannot be driven 
off by heat. Some coals which do not yield a good quality of 
coke can be mixed to advantage with a good coking coal. 



60 ELEMENTS OF INDUSTRIAL CHEMISTRY 

The chief use of coke is for metallurgical purposes, but a great 
deal is used in gas producers, on railroad engines and for domestic 
purposes. 

The objection to the use of coke made in by-product ovens 
seems to have been without foundation, and the relative amount 
of coke made in the by-product ovens has increased steadily and 
rapidly. It seems that in a short time most of the coke made 
in this country will be made in this way, the increase being lim- 
ited only by the demand for the by-products. 

LIQUID FUELS. The only liquid substances which have any 
extended use as fuels are crude petroleum and various products 
obtained by its fractional distillation; as petroleum spirit, lamp 
oil, and the residue or " residuum " left in the retort after the 
distillation of the lubricating oils. Tars obtained as by-products 
in other industries are sometimes burned as fuels when a more 
remunerative market is not available, but they are too expensive 
for this purpose. The objection of expensiveness applies also to 
alcohol at present, but as it possesses certain advantages as a 
fuel, and its production is subject to our control, it is possible that 
it may assume more importance in the future if it can be pro- 
duced more cheaply. 

Petroleum. Petroleum is widely distributed, but 86 per cent 
of the world's output comes from this country and Russia; the 
United States producing 63 per cent and Russia 23 per cent of 
the total. In this country the Pennsylvania fields have been 
most prominent, and it was here that oil was first obtained by 
systematic borings. Besides Pennsylvania, many other States 
have become oil-producing. 

In using crude petroleum as a fuel the greatest objection is 
that the volatile portions will escape and mix with air and form 
an explosive mixture, as it requires only small amounts to form 
an explosive mixture with air. But it is only necessary to remove 
these by distillation to avoid such danger. 

In burning crude oil in 'furnaces it is first converted into a very 
fine spray by means of special burners, and the spray directed 
against refractory material, which, becoming incandescent, trans- 
mits much heat to the boiler by radiation, and it also effects better 
combustion. These burners are operated in two ways. In the 
first, the oil is " atomized " by forcing it under pressure through 
burners so constructed as to send the oil into the furnace in a sheet 
of finest spray. By the second the same disintegration of the 
oil is accomplished by a jet of steam. The objection to the 



FUELS 61 

second method is that a large amount of steam is consumed, 
and the flame is cooled down at the point where the combustion 
should be most rapid, and, while the steam is effective in securing 
the combustion of the last portions and preventing the formation 
of smoke, it can be best introduced later in the flame and in 
smaller amounts. 

Several advantages are obtained by using petroleum as a fuel. 
It has a high calorific value, from 10,000 to 10,500 calories, is 
more uniform than coal, is easily regulated to secure complete 
combustion, and the rate of combustion can be changed by merely 
turning the valve admitting the fuel. It does not deteriorate if 
kept in covered tanks, and no spontaneous combustion occurs. 
It requires a small fraction of the number of stokers required to 
burn coal, gives no ashes, cinders or smoke when properly burned, 
and is easily transferred at sea through flexible hose by pumps. 

Still the output is so small when the total amount of fuel 
consumed is considered, and the supply so uncertain, that it seems 
that petroleum as a fuel must remain an adjunct except near the 
sources of supply and for certain special purposes such as on fast 
ocean-going ships, for use in navies, and to assist in meeting 
sudden demands on power-houses of a temporary character. 

GASEOUS FUELS. When the products of combustion of 
solid fuel are allowed to pass through a bed of incandescent carbon 
they are partially reduced, and can be ignited on their escape. 
The pale blue flame often seen burning at the top of an open 
grate fire is an illustration. And if the fuel bed were sufficiently 
thick and hot enough to reduce most of the carbon dioxide and 
water formed at the bottom of the grate, and provision made for 
collecting the gas, we should have a sample of producer gas. 

Producer gas is, then, the combustible gas obtained by the 
burning of solid fuel with a restricted supply of air, or with air 
and steam together in such a way that there is subsequent reduc- 
tion of the products of combustion and the steam by incandescent 
carbon. When air alone is used, the gas is called " air gas. 7 ' 
When steam is blown in along with the air the gas obtained is 
called " semi-water gas." By the action of steam alone on heated 
carbon the product is " water gas." 

Producer gas has the lowest calorific value of any gaseous 
fuel, and the temperature of its flame is the lowest of any, yet it 
is the cheapest artificial gas per unit of heat. It has become of 
great commercial advantage, as nearly any kind of solid fuel can 
be converted into a gaseous fuel in the producer. Although about 



62 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



20 per cent of the total heat of combustion of the fuel is lost in 
the producer, the remainder can be used so efficiently that the 
loss is more than retrieved. Its use in connection with the gas 
engine is an efficient means of power generation. With care it 
can be burned with a small excess of air, and complete combustion 
secured, causing a smaller amount of heat to be carried away 
by the escaping gases. 

It is finding application in commercial work of many kinds 
where a gas of high calorific value is not required. 

Siemens' Regenerative Furnace. The method used in con- 
nection with the Otto-Hoffmann oven above, for recovering the 
heat from the flue gases is known as the regenerative system. 




Fig. 33. 



Fig. 33 is an illustration of this type of furnace, which was first 
worked out by Siemens in connection with his gas producer, 
and known as the Siemens " regenerative " furnace. Beneath 
the furnace proper, A, are four chambers, B, C, D, and E, filled 
loosely with firebrick. The gas and air enter through B and C, 
and after burning pass out through D and E. After the interior 
of D and E is highly heated the direction of the gases is reversed, 
the gas and air entering through D and E, where they are highly 
heated before burning, and escape through A and B. Various 
methods have been worked out for the recovery of the heat con- 
tained in the gases which escape hot after the completion of an 
operation. This is illustrated in the Otto-Hoffman and Semet- 
Solvay coke ovens above, and in connection with gas producers 



FUELS 63 

it is a matter of considerable importance to use as much as possi- 
ble of the heat of the escaping gases to preheat the air and steam 
introduced into the producer. 

Water Gas. Steam is usually forced into the gas producer 
along with air to overcome practical difficulties encountered in 
operating the producer with air alone, and at the same time to 
increase the calorific value of the gas. As the action of steam on 
carbon is accompanied with an absorption of heat, it is necessary 
to supply heat to continue the operation. The production of 
" semi-water gas " is made a continuous operation by the heat 
generated by the action of the oxygen of the air on the fuel in 
the producer. By separating the two operations taking place 
in the formation of " semi-water gas," and collecting the result- 
ing gases separately, we would obtain " air gas " and " water 
gas." The intermittent operation of the producer with air and 
steam is the usual method of preparing water gas. The producer 
is operated a few minutes with air until the temperature is suffi- 
ciently high, when steam is passed in until the temperature falls 
too low to produce a gas of high calorific value. 

The action of steam on highly heated carbon results in the 
formation of carbon dioxide, hydrogen, and carbon monoxide in 
proportions varying with conditions. It is customary to express 
the action by the following two equations: 

(1) 2H 2 0+C = CO2+2H2 - 18,340. 

(2) H 2 0+C = CO+H 2 - 28,650. 

At low temperatures the reaction is mostly according to Eq. 
(1) while at more elevated temperatures, according to Eq. (2). 

As the gases formed by these two reactions are capable of 
reacting according to Eq. (3) CO 2 +2H^CO+H 2 O-9310, and 
since equilibrium is obtained more readily between gases than 
between a solid and a gas, the composition of the water gas 
will tend to approach the condition of equilibrium according 
to this equation. 

The producer used to generate water gas does not differ greatly 
from the ordinary gas producer. The first successful water-gas 
plant was worked out by Lowe in 1874. 

Coal Gas. Coal gas is made by the destructive distillation 
of coal in fireclay retorts of special construction. They are 
mounted above a gas producer which furnishes the gas with which 
the retorts are heated. Above is a fireclay arch. Each retort 



64 ELEMENTS OF INDUSTRIAL CHEMISTRY 

effects the distillation of a charge of about 400 lbs. in four hours. 
The gas escapes through a cast-iron mouthpiece which closes 
the open end of the retort and into a common main, where the 
opening of each tube is water sealed to prevent back pressure 
when the retort is opened. 

The composition of the gas varies with the kind of coal used 
and the conditions during distillation. These cause greater 
change in the illuminating power than in the calorific value. 
It burns with a bright, often sooty flame, and as it is composed 
almost entirely of combustible gases it has a high calorific value. 
The coke left in the retort is of inferior quality because of the 
method used to effect distillation and the character of the coal 
necessary to form a good quality of gas. 

It is used principally for illuminating purposes, and on ac- 
count of its high calorific value, it is used to some extent where 
a great deal of fuel is not needed. 

Oil Gas. Oil gas is made by the destructive distillation of 
petroleums. It is somewhat similar to coal gas, and contains 
a considerable amount of unsaturated hydrocarbons which im- 
part luminosity to the flame. 

Natural Gas. Natural gas occurs ready formed in the earth, 
and in the oil regions of Pennsylvania and Russia it is found in 
enormous quantities. It always accompanies petroleum, and 
their origins are closely connected. It is frequently confined 
under great pressure, and when borings are made through the 
overlying strata its escape is at times beyond control. While 
it always accompanies petroleum, it is sometimes found alone. 

As it is composed almost entirely of combustible gases, its 
calorific value is very high. The natural gas of this country 
burns with a slightly luminous flame, and has a higher kindling 
point than other gaseous fuels. When it is properly burned it 
is an excellent fuel, because of its high calorific value and prac- 
tically smokeless flame, 



CHAPTER IV 
SULPHURIC ACID 

PROPERTIES. Concentrated sulphuric acid is a heavy, 
oily liquid, which is colorless and odorless when pure. Its 
density is about 1.9, boils at 290° C. and freezes at about 10° C. 
The strong acid has a very powerful dehydrating action, break- 
ing down the skin and many other organic substances by robbing 
them of their water, in some cases even carbonizing or blacken- 
ing them. Burns produced by sulphuric acid are best treated 
by the instant application of large quantities of water, followed 
by the application of a solution of sodium bicarbonate and 
then dressing the w r ound with an emulsion of limewater and lin- 
seed oil. Impure acid attacks practically all metals, including 
platinum. Acid stronger than 65 per cent has no action on 
iron, while that less than 65 per cent has no action on lead. 

OCCURRENCE. Sulphuric acid is found in commerce as: 
Chamber acid (about 53° Be., 66.6 per cent H2SO4) taken from 
the bottom of the chambers in the chamber process; Glover acid 
(about 60° Be., 77.7 per cent) taken from the first or Glover 
tower of the chamber process; 66 acid is fairly pure acid con- 
centrated to 66° Be., 93.2 per cent; 98 acid, of 98 per cent, 
made by concentration or by the contact process and generally 
of great purity; oleum or fuming acid (100 per cent H2SO4 con- 
taining additional SO3 in solution), made by distillation of sul- 
phates (obsolete) or by the contact process: Nordhausen acid 
(oleum when made from distillation of weathered shales [obso- 
lete], containing iron sulphate or from FeSCk), approximating 
a composition H2SO4SO3 or H2S2O7, which is pyrosulphuric acid; 
and oil of vitriol, also called o.v. (generally about 66°). The 
old name, " oil of vitriol," is derived from its first preparation 
by the alchemists Gaber, Valentine and their predecessors, who 
made it by distillation of sulphates, particularly green vitriol, 
FeS04, or by the burning of sulphur after the addition of salt- 
peter. In fact, historically, sulphuric acid is one of the first 
isolated acids, known to the Arabians in the eighth century and 

65 



66 ELEMENTS OF INDUSTRIAL CHEMISTRY 

to Europe in the fourteenth and fifteenth centuries, when chemi- 
cal industries really began to develop. 

RAW MATERIALS. The three principal sources of sulphuric 
acid are: native sulphur, sulphide ores, and waste gases from 
metallurgical and technical operations. The chief supply of sul- 
phur in this country is from the Louisiana beds. This is an under- 
ground deposit which is being successfully worked by the Frasch 
process. Iron pyrites, often carrying more or less copper sulphide, 
is, at present, the largest source of sulphur for acid making. The 
chief supply of pyrites comes from Spain, although a limited 
quantity is obtained from other countries and a small amount 
from Canada and the United States. The third source of supply 
is from the " fumes " from the sulphide smelters. These gases 
were formerly allowed to go to waste, but are now being util- 
ized to some extent. 

OUTLINE OF PROCESS. Before describing the various 
operations involved in the manufacture of sulphuric acid it may 
be well to give a brief outline of the general process, later return- 
ing to consider the various steps more in detail. Thus, starting 
with the ore, it is crushed to get it to a uniform size con- 
venient for handling. The ore, or sulphur if that is used, is burnt 
in the appropriate form of furnace. By the combination of the 
sulphur with the oxygen of the air, the gas sulphur dioxide is 
produced. Regardless of the form of furnace, or the nature of the 
raw material, the hot sulphur dioxide immediately passes over the 
niter pots, where it is brought into contact with vapors of nitric 
acid. This nitric acid is formed by treating sodium nitrate with 
sulphuric acid, and is for the purpose of keeping up the supply 
of nitric oxides, which in their turn act as oxidizers for the SO2 
by converting it to SO3. As the sulphur dioxide, now mixed with 
nitric acid, leaves the niter pots, it passes through a dust chamber, 
where it comes in contact with baffle plates, thus causing the dust 
to be deposited. The dust-free gases next pass into the bottom 
of the Glover tower and work their way up through a bed of porous 
material over which is flowing a mixture of dilute sulphuric acid 
and nitrosvl-sulphuric acid from the Gay-Lussac tower. The 
nitrosyl acid, being decomposed by the dilute chamber acid, gives 
off nitrogen oxides which tend also to oxidize the SO2 to SO3. The 
SO3 thus formed combines with the dilute sulphuric acid, thereby 
converting it into strong acid. The strong acid from the bottom 
of the Glover tower is in part used over in the Gay-Lussac tower, 
the remainder going to storage tanks. The gases from the top 






SULPHURIC ACID 67 

of the Glover tower pass into the first lead chamber, where they 
meet with water in the form of steam or spray and with a supply 
of oxygen. Most of the remaining SO2 is converted into SO3 in 
the first chamber, which on account of the presence of moisture 
at once forms sulphuric acid. The color of the fume in the first 
chamber is of a heavy white character, due to the formation of 
the sulphuric acid. The gases pass from the first to the second 
and then to the third chamber. In so passing the content of sul- 
phur oxides becomes less and less, while the content of oxides of 
nitrogen becomes more concentrated. The oxides of nitrogen 
having accomplished their purpose are now recovered by passing 
into the Gay-Lussac tower, where they are absorbed by means 
of concentrated sulphuric acid. The nitrosjl-sulphuric acid, 
(NCfeHOSC^), produced in the Gay-Lussac tower is pumped to 
the top of the Glover tower, where it is decomposed by the weak 
chamber acid, and the oxides of nitrogen again returned to the 
system. 

The acid formed in the chambers goes by gravity to the 
storage tanks, from which it is pumped to the evaporating pans 
for concentration. 

Having taken a hasty glance of the general method employed 
in making sulphuric acid, let us now take up the steps more in 
detail so as to get a better understanding of the process as a 
whole. 

SULPHUR BURNING. In burning sulphur three points 
chiefly have to be considered: i.e., freedom of the gases from vol- 
atilized sulphur which has not been oxidized, sufficient richness 
of the gases for profitable operation of the sulphuric- acid -making 
portions of the plant, and as complete removal as possible of 
sulphur from the slight residue of mineral matter. Provision 
must be made for maintaining a sufficiently high temperature of 
the surrounding walls and of the material on which the sul- 
phur is supported. For the latter purpose an iron plate is 
generally used — Cast iron preferred — and it should be heavy 
enough and hot enough to insure active combustion of the 
sulphur at all points, even where the collected mineral residue 
is practically all that is left and only a small percentage of 
sulphur is being burned out of it. For this purpose special 
ovens are constructed. The necessity for accurate draft regu- 
lation is apparent. Too much draft is better than too little 
if ample provision has been made for the complete interaction 
of the gases before they are allowed to cool. In some types of 



68 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



burners, in which the gases are drawn away too quickly from 
the burning pan, an excessive supply of air serves to chill the 
vapors and promote the deposition of sulphur in the flues. 

Fig. 34 illustrates one type of furnace recommended. The 
burner consists essentially of a shell of brickwork having an 
upper and lower chamber, the division between the two acting 

as a reverberatory over 
the pan A, in which 
the sulphur is burned. 
Draft is regulated at 
the door E. The fire 
cooled when neces- 




Fig. 34. 



is 

sary to retard the vapo- 
rization of the sulphur 
by means of admitting 
the air to space B be- 
neath the plate. Prod- 
ucts of combustion pass 
up through the hole C 
into the upper chamber 
D, where opportunity 
is given for the inter- 
action of sulphur vapor with the excess of air. A division wall in 
this upper chamber insures longer passage of the gases before 
cooling. A small hole above the inlet opening C into this upper 
chamber admits more air if necessary for the complete combustion 
of the sulphui vapor. Iron supports are provided for a niter 
pot when it is preferred to furnish niter for the chambers in this 
manner. This is one of the intermittent type of burners, 
generally operated in batteries. The exact regulation of draft is 
very difficult, and extreme care in periodic rotation of charges 
is essential to successful operation. 

BURNING OF PYRITES, Like coal, pyrites ore was not rec- 
ognized as a combustible' until early in the last century, various 
claims dating from 1793 to 1820. 

The first step in the burning of pyrites is properly to adapt 
the size of the ore to the character of burner being used. Although 
ore may be purchased on contract relatively free of fines or small 
ore, it is generally desirable to render the plant as independent 
as possible of market conditions. If run of mine ore is pur- 
chased, lumps may exceed 12 or 14 ins. diameter and a heavy 
breaker of the general Blake pattern, illustrated in Fig. 2, should 






SULPHURIC ACID 



69 



be provided and located preferably below the ground level. 
Feeding should be done from an iron-sheathed plank or 
cement floor. If lump ore is to be burned the product of the 
breaker should be elevated to a rotary screen of punched metal 
plates | to | in. in thickness the holes in which are f in. in 
diameter. The amount of fines made will be dependent upon 
the diameter of these holes, the character of the ore and the 
speed of the crusher. From the rotary screen, or riddle, the fines 
should be allowed to fall into a small hopper, and the lumps into 
a larger one. If all ore is to be burned as fines there should be 
placed, preferably below the breaker, one, or better, two sets of 
rolls illustrated in Fig. 4, and the breaker should be set some- 
what closer. * The breaker may then be expected to reduce the 
ore to about 1J to 2 ins., the first rolls to 1 in. and the second rolls 
from 1 to | in. or less. For the delivery of fines ore to fines burners 




Fig. 35. 

a belt conveyor is well adapted, and link-belt carrier conveyor 
with tripper has been used. 

Lump Burners. The lump burner is the simplest form of 
deep-bed coal fireplace. The charges required are weighed 
out with moderate accuracy and placed before each burner, 
each furnace being furnished with a regular size of lump. 

Fig. 35 shows a good type of burner, in which the common 
flue is provided with a double arch top. All doors are either 
hinged or their faces inclined, carefully planed, and therefore 
swing by gravity or latch against the planed edges cf the door 
jamb, allowing little leakage. The ash pit door D is perforated 
with 7 or more 1-in. holes, which can be plugged to regulate the 
admission of air below the grates. The doors E admit the 
shaker to the grate bars and also permit, to some extent, 
barring near the grate level. The doors C are likewise pro- 
vided for the latter purpose, raising large scars to the surface 



70 ELEMENTS OF INDUSTRIAL CHEMISTRY 

of the bed, but are ordinarily not often required and may be 
made of the slide pattern and puttied tight if desired. Through 
the door B the charges are introduced, and distributed as quickly 
as possible over surface of 'ohe fire bed. The upper doors F, 
also slide doors, are not open except for occasionally cleaning the 
upper flue and may therefore be puttied up between times. The 
cross-section of the upper flue should be carefully figured to avoid 
rapid currents of gas that would interfere with the exit of gases 
from the individual burner. These burners are generally built 
from 4 to 5 J ft. wide and 4 to 6 ft. from front to back. Fig. 35 
also shows one method of potting niter (for supplying the nitric 
oxides to the chambers). The nitrate of soda and sulphuric 
acid are charged through a covered hopper K, into the cast- 
iron vessel H, which is supported on a plate in an enlarge- 
ment of the common flue. Being thus subjected to heat from the 
burner, the nitric acid is distilled out. The door J is provided 
for removing the entire vessel. 

All work that it is necessary to do with the burners should 
be done as rapidly as possible, so that doors may be open the 
minimum time. The successive rotation of the burners should 
be as regular as clockwork. If the number of burners in a set 
(frequency of charging) is such that two burners are to be charged 
at once they should always be as nearly as possible diagonally 
opposed to each other on opposite sides of the set, and the rota- 
tion should be so arranged that the period of greatest heat occurs 
in burners half the length of the burner set from each other. 
No red-hot ore should ever come through the grate bars; in fact, 
working with any usual depth of fuel bed, the ore when shaken 
down should be fairly cool. Proper burning of the cinder is 
superficially indicated by lightness, porosity of surface and a 
clear red, brown, or black shade (according to the character of 
ore) with little evidence of mottling, streaking or apparent hard 
spots. When broken the ore should show no kernel or hard 
center, but should have substantially the same texture through- 
out, except right at the suiface it is likely to be more porous and 
frequently is checked by numerous cracks. 

Fines Burners. Owing to the difficulty encountered in the 
burning of fine ore a number of forms of mechanical furnaces 
have been invented. The two latest and those used most in 
this country are the O'Brien and the Wedge burners. Even 
though the former is almost a toy as compared with the latter, 
it fills its place in smaller works, burning 5 to 15 tons a day. 



SULPHUEIC ACID 



71 



The best running capacity of the O'Brien on high-grade ore smaller 
than i in. is about 6000 to 7000 lbs. per day. The same furnace 
can properly burn 9000 or even 10,000 lbs., but repairs become 
excessive. Wedge furnaces range from 12 to 32 ft. in diameter, 
with five to seven hearths. The 21J-ft. furnace has a capacity of 
28,000 to 48,000 lbs., and weighs about 304 tons. 

The O'Brien Burner. Fig. 36 shows the O'Brien burner, the 
mechanical features of which need little explanation. The 'cen- 
tral shaft A is cooled by the vertical current of air passing up 
through it, The arms B are likewise hollow and subdivided 
lengthwise nearly to the outer 
end in such a manner that a 
portion of the current of air 
is drawn out sidewise through 
one side and back again to the 
hub by the draft of the central 
shaft acting as a stack. The 
arms are secured by hubs C 
tightly fitting into the central 
shaft. The inner end of the 
arm tapers, is inserted with 
the blades D turned sidewise 
and locks with a quarter turn 
on its own axis in the direc- 
tion which the drag of the ore 
on the blades along its bottom 
tends to continue. Thus the 
action of rotation around the 
central shaft tends to lock the 
arms more firmly into the hubs, 
at the same time they can be 
turned up in the opposite direction by a special tool, removed 
and replaced in a few minutes. The rabble blades are cast as 
part of the arm, and given an angular position. They are carried 
around the central shaft, slowly moving the ore outward or inward 
on the alternate shelves. The shelves, raked inward, have an 
opening E around the central shaft through which the gas passes 
up and the ore falls down. The alternate shelves have openings 
F at the periphery for the same purpose. A screw feed from the 
hopper G gives an excellently regulated supply of ore and the 
cinder passes out through the bottom chutes H that supply a 
portion of the air for burning. Two doors I are provided to each 




Fig. 36. 



72 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



shelf for removal of arms and have wheeled draft openings J 
that serve also as peep-holes for observing temperatures. Rota- 
tion is imparted to the shaft 4 by a very cheap and simple 
gear which is nearly the whole diameter of the burner and 
is made by bolting segmental sheets L of i^-in. steel to a 
flange M on the lower end of the shaft, uniting the periphery 
of the circular plate thus formed with cheap cast-iron sections of 
curved racks N which in turn rest upon small pinions 0. If any- 
thing catches inside the burner the weight of the rack becomes 
insufficient to keep the gears meshed and the racks jump without 
breaking or injury, only making enough noise to call attention 
quickly to the trouble. A vertical chain drive P actuates the 
large sprocket on the screw shaft Q from the main pinion shaft 
below. 

The Wedge Burner. The Wedge burner, Fig. 37, is naturally 
more substantial in every respect, as required by its heavier 

duty. The central shaft A is 
large enough to admit a work- 
man, its temperature being at 
all times low enough to per- 
mit his making any repairs 
that may be necessary. Each 
arm B is separately water- 
cooled and strongly secured 
to the shaft by a heavy breech 
lock C, also water-cooled, 
while the rabble blades are 
individually removable and 
replaceable with practically no 
interruption of the furnace. 
The hearths are level and have 
openings E near the shaft and 
F at the outer edge for drop- 
ping ore and permitting the 
rise of gases. The entire top 
of the burner G serves as a 
combined feed hopper and 
feed table, being provided 
with its own special arms and tripper rakes that swing back 
under the excessive load of deep-piled ore, thus regulating the 
feed at the center even if the ore is piled high at the sides, 
at the same time gradually distributing such a pile evenly. The 




Fig. 37. 



SULPHURIC ACID 



73 



supply of ore entering around the shaft through a sand-lute 
continually renews the lute and further regulates the feed, cinder 
being discharged through the chute H. Repair doors /, poke 
and peep-holes J are likewise provided. The central shaft, all 
arms and moving parts are supported on the gear M, by means 
of the four roller bearings N, traveling on the smooth outer face 
of the gear, the whole being merely centered by the bottom pin P, 
giving a rigid central shaft with no " steppe" or base block, prac- 
tically without wear, friction being almost wholly rolling. Obvi- 
ously the feed is here strictly dependent on the operation of the 
rake arms and over-feeding or clogging is almost impossible, as 
is also the failure of the water-cooled arms. Nevertheless the 
driving pinion is actuated by a shear pin in the hub of this 
pinion that cuts off if any serious obstruction takes place in the 
furnace. 

Dust Prevention. As the gases come from the furnace they 
are more or less loaded with fine dust carried along mechan- 
ically by the draft. This dust if allowed to enter the Glover 
tower would result in serious difficulties. Although the fines 
burners have many advantages over lump burners, the amount 
of dust carried into the system is far greater in the former method 
of burning the ore. It be- 
comes necessary, there- 
fore, to remove this dust 
or at least reduce its 
quantity. In the oldest 
method the gases were 
allowed to pass into a 
large chamber, where the 
current was slowed down 
to a marked degree, thus 

allowing the dust to settle out. Baffle plates or walls were then 
introduced into the chamber and found to give much better 
results. These dust chambers are still used to quite an extent 
even to-day, an illustration of which is shown in Fig. 38. 

Centrifugal separators have been invented by A. P. O'Brien, 
which are entirely feasible when used in conjunction with a fan. 
He has also adapted them to serve as niter ovens, by placing the 
pots in the bottom of the conical body. The most effective 
form of separator is that recently introduced by Henry Howard, 
which consists of a series of horizontal parallel shelves an inch or 
so apart, across which the gases pass in a slow steam from the 




Fig. 38. 



74 



ELEMENTS OF INDUSTKIAL CHEMISTRY 



general inlet chamber to the general outlet chamber. The results 
obtained are truly astonishing, even dust ordinarily regarded as 
impalpable being largely retained. 

Glover Tower and Its Reactions. The gases as they 
come from the burners usually contain from 6 to 8 per cent of 
SO2, which as they pass over the niter pots become somewhat 
oxidized, thus bringing to the Glover tower a mixture of sulphur 
dioxide, sulphur trioxide, oxygen, nitrogen, some oxides of nitro- 
gen, a small amount of moisture and a little dust. As these 
gases come in at the bottom of the tower they meet the mixed 
dilute sulphuric and nitrosyl-sulphuric acids flowing down the 
stack. Considerable heat is generated at this point, concentra- 
tion of the dilute acid occurs 
and the following reaction 




probably takes place: 

2NO2HOSO2+SO2+2H2O 
= 3H 2 S0 4 +2NO. 

The sulphuric acid formed 
here together with the SO3 
combine with the dilute acid, 
thus producing a fairly strong 
acid known as " tower acid." 
The gases not absorbed by 
the dilute acid pass up the 
tower, various reactions tak- 
ing place as they progress, 
finally leaving as a mixture of 
S0 2 , S0 3 , NO, N2O3 and 2 . 
The Glover tower must be 
built to stand the severest 
duty and is well illustrated 
in Fig. 39. The interior is 
of heavy lead construction 
and is filled with acid proof 
brick. At the top is an 
arrangement for the proper control of the supply of nitrosul- 
phuric acid and dilute acid, the former being introduced to 
furnish the nitrogen oxides and the latter to decompose the former. 
Chamber System and Reactions. Fig. 40 illustrates a 
typical arrangement for the chamber process. Near the top of 
the Glover tower is a favorite place for locating a fan (4) which 



Fig. 39. 



SULPHURIC ACID 



75 



takes the gases from the Glover to the first of the lead chambers. 
It is customary to make the first chamber (5) fairly large, as the 
gases are at first converted rapidly. In this chamber the gases 
come into contact with water in the form of steam or spray and 
with atmospheric oxygen. Here about one-third of the entire 
output of a plant is formed. Many and complicated reactions 
take place in this chamber as well as in the following chambers. 
The conditions of working prevent a definite knowledge being 
obtained, so that it is a matter of theory and each authority 
has his own particular theory. Certain definite changes do, 




ffiw€m 



Fig. 40. 



however, take place which may be expressed in the following 
reactions: 

S0 2 +N 2 3 = S0 3 +2NO; 
S0 3 +H 2 = H 2 S0 4 ; 
2NO+0 2 = 2N0 2 . 

Thus it is that the oxides of nitrogen serve to convert the 
sulphur dioxide to the trioxide, which in the presence of air 
revert to their original condition and again repeat the cycle. 
As the ga-es pass from the first to the second chamber and then 
to the third chamber the content of sulphur oxides becomes 
less and less, until finally in the last chamber their composition 
is largely a mixture of XO and N0 2 or what is usually spoken 
of as N2O3. 



76 ELEMENTS OF INDUSTRIAL CHEMISTRY 

The Gay-Lussac Tower and Its Reactions. The gases 
coming from the last chamber are passed into the Gay-Lussac 
tower, which is somewhat similar to the Glover tower in its 
construction. Into the top of this tower, however, is introduced 
a supply of concentrated sulphuric acid obtained from the bot- 
tom of the Glover tower. The gases meeting this strong acid 
are absorbed according to the following reaction: 

N 2 3 + H2SO4 = 2NO2HOSO2 + H 2 0. 

The nitrosyl-sulphuric acid thus formed is pumped to the 
top of the Glover tower, where it is used to furnish the oxides 
of nitrogen for the chamber reactions. 

CIRCULATING SYSTEM. It is now proper to describe in more 
detail the acid circulating system and the apparatus provided 
for this purpose. It will be apparent that large quantities of 
acid have to be elevated to the tops of the towers. Calculation 
shows that the nitrous gases for their sufficient recovery require 
that an amount of 60° Be., equivalent to 60 per cent of the total 
production of the chambers, be run down the Gay-Lussac per 
day. In practice this is generally 90 to 150 per cent. When 
intensive work is used, 150 to 300 per cent is needed. 

This lifting has almost universally been done by compressed 
air admitted into vessels, Fig. 41. These " eggs " are filled 

with acid through a pipe contain- 
ing some form of check valve that 
prevents its return. Air is then 
automatically or manually ad- 
mitted through another pipe. A 
third pipe from the bottom of the 
vessel permits the acid under 
pressure to leave the vessel fol- 
Fig. 41. lowed by the rush of air of equal 

or slightly greater compressed 
volume than the acid pumped— a method wasteful in the extreme. 
Fig. 42 shows one of the automatic Kestner lifts attached to a 
small acid egg, the operation of which will be apparent from 
the illustration. These Kestner lifts have been used for years 
by many of the largest acid manufacturers and have given entire 
satisfaction. Moderately heavy walled lead pipe is used through- 
out the chamber plant for the transportation of acid. Recently 
lead-lined iron pipe has found great favor for that portion of 




SULPHURIC ACID 



77 



the acid lines subjected to very heavy pressure (like those from 
the eggs to the heads of the Gay-Lussac tower) or to jars by 
reciprocating pumps or lifts. 

Geared pumps if made of iron ffrfr 

require excessive repairs. Stone- [5, 

ware pumps have not this objec- 
tion, but are hardly safe to use 
above 30 lbs. pressure or 40 ft. 
acid-head. Centrifugal pumps, 
arranged in stages, have been 
tried with excellent success for 
low lifts of strong acid, but in 
[he chamber work all of the acid 
is 62° or weaker and the neces- 
sity for perfect regularity of 
opeiation makes it undesirable 
to multiply the mechanical 
devices necessary to accomplish 
the single lift. Positive acting 
steam pumps have been used 
successfully for acid, but are 
corroded and it is doubtful 
whether they are any more 
economical than the best air lifts 
(Pohle) where the necessary depth is obtainable. Pohle lifts 
consume only about half the air required for blowing by eggs, 
furnish a steady stream like a pump, are without moving parts 
and can be made practically free from wear. 

MOVEMENT OF GASES. The fans used for actuating the 
gases in the chamber system are of three types, according to loca- 
tion, between the dust chambers and the Glover, between the 
Glover and the acid chambers, or between the acid chambers 
and the Gay-Lussac. 

In the first case a steel fan, water cooled, is used very success- 
fullt in handling the hot gases; in the second place a regulus metal 
fan is frequently used and in the third instance a stoneware 
fan may be employed. 

Purification" of Sulphuric Acid. Sulphuric acid as 
manufactured in the chambers, particularly as concentrated in 
the Glover tower, exhibits certain impurities that are quite 
important from an industrial point of view. These are lead, 
iron, arsenic, selenium, antimony, aluminum salts, nitrous oxides 




78 ELEMENTS OF INDUSTRIAL CHEMISTRY 

and nitric acid, platinum, mercury, the alkalies, calcium, and 
copper. It is found that if the acid is treated with H2S for the 
lemoval of arsenic, practically all other impurities are removed 
at the same time and the acid is even clarified from some inert 
suspended matters that are undesirable in appearance only, 
if, however, a thoroughly pure and limpid acid is required, there 
is practically no way of obtaining it except by distillation on 
the one hand or the use of the contact system on the other. 
Sulphuric acid as made in the chambers will vary in its arsenic con- 
tent from about 0.1 per cent up to about 0.3 per cent according to 
the ore used and the amount of dust carried over from the burners. 

Of the various methods used for the precipitation of the 
arsenic and other impurities by generation of the H2S within the 
liquid, probably the best, and certainly the most frequently used, 
has been the precipitation vyith barium sulphide. The advan- 
tages presented by barium' sulphide are twofold. First, the 
barium itself is precipitated as sulphate in the liquor and adds 
greatly to the weight and density of the precipitate. Second, 
substantially no soluble material is left in the liquor to inter- 
fere with subsequent concentration or use of the acid. The 
acid, however, must be diluted to sp. gr. 1.4 containing 50 per 
cent of H2SO4. To obtain the best results it must then be heated 
to about 80° C. and a warm solution of barium sulphide 7J° 
to 8° Be. run in at the bottom of the vessel in such a manner as 
to prevent the escape of H2S. The most convenient way of doing 
this is to divide the liquid through as many small openings as 
will permit the passage of the gas without plugging up by forma- 
tion of the precipitate. These openings may preferably be placed 
beneath a perforated shelf of lead, or a ribbed shelf without 
perforations but around the edges of which are serrations to divide 
the bubbles of gas again. The separation of the purified liquid 
from the mud may be carried out by either of the usual nitration 
methods. The only objection presented by the barium sulphide 
treatment is that the purification cannot be carried so far in this 
way. Nearly double the amount of arsenic remains in the acid. 
This can, of course, be removed by subsequent treatment with 
gaseous H2S, but if the treatment by gas is to be undertaken, the 
whole operation might better be carried out by the gaseous 
method. 

The Concentration of Sulphuric Acid. Two systems of 
concentration, illustrating the wide range of principles employed 
in practice, will be described. 



SULPHURIC ACID 



79 



The first installation, Figs. 43 and 44, will be that likely to 
be found in a chemical plant manufacturing a good grade of 66° 
acid. The acid will have 
been purified in some man- 
ner, probably by the use of 
H2S gas, and will be ap- 
proximately 46° Be. Lump 
burners will be found of the 
usual type except that prob- 
ably the flue above the 
arches will be somewhat 
higher at one end. 

The common flue above 
the burner is crossed at 
suitable intervals with sup- 
porting beams, set in reinforced concrete. Beginning vvith the 
burner furthest away from the supply of acid, the flue is 
very low, increasing in height toward the acid supply end. 
This results from the successive rise of the lead pans to 




Fig. 43. 




Fig. 44. 



allow for the downward flow of the acid. Upon these protected 
I-beams are laid cast-iron plates, If ins. thick at the lower 
end and 1 in. at the upper end furthest away from the burner 
arch. Passing backward along the flow of the acid each of the 
beams is raised 1 in. higher than the preceding. On the iron 
plates a layer of coarse sand is placed, as thin as can be made 
with absolute certainty of everywhere having a separation of 
sand between the iron and lead in order to prevent immediate 
contact between them, as these points would thus become over- 



80 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



heated and cause excessive corrosion of the lead. Two or three 
layers of thin asbestos paper may be used instead of the sand. 
The pans vary gradually in depth from 8 to 14 ins. and vary also 

in thickness. After the pans 
are all in place the long double 
edges where they abut are bent 
over to form lips. 

From the series of pans 
Fig. 44, the acid continues its 
downward flow into another 
series of pans Figs. 45 and 46, 
which may immediately adjoin 
the first series or be located 
in an entirely different build- 
ing. These pans utilize the 
waste heat from the higher concentration apparatus to be 
described, and are located over the flue supported on perforated 
cast-iron plates. These plates give a larger output with entire 
safety and better fuel economy, but do not serve to protect 
the flue below as do the solid plates rimmed around the edge. 




Fig. 45. 




Fig. 46. 



The acid then flows from the pan to the platinum still, the rate 
of flow being regulated automatically. 

PLATINUM STILLS. Many shapes and patterns of platinum 
stills have been designed and special advantages claimed for 
each. In all probability the net result is just about the same in 
the long run except that the lower and longer pans are more 
economical of platinum. Some stills are provided with baffle 
partitions, causing a circuitous flow of the acid through the 
still, the advantage claimed for these being that a better concen- 
tration is obtained in a single operation. Against this must be 
set, not only the small increase in platinum, but also the very 



SULPHURIC ACID 81 

great increase in liability to leakage and in irregular strains on 
the bottom of the pan. Corrugated bottoms are used in some 
patterns of platinum still. They present about 60 per cent 
more surface for transfer of heat, but on the other hand, increase 
to some extent the difficulty of making side joints and conse- 
quently the liability to leakage. They have, however, the advan- 
tage of stiffening the bottom. Lining with gold has been found 
greatly to increase the life of the platinum pan and, at the present 
relative prices of gold and platinum, is a very marked saving. 
Gold resists about seven times as well as platinum. The gold 
is not plated on or attached by dipping, but must be attached by 
the method invented by one of Heraeus's assistants. The over- 
heated gold is poured on top of the platinum ingot heated nearly 
to fusion, forming a double ingot, which is then rolled into the 
sheet to be made up into stills. 

Owing to the prohibitive cost of platinum it is being aban- 
doned almost completely in England. Better designed stills 
with tile lining, Kestner stills, towers, or silica dishes in cascade 
are rapidly replacing it. 

THE CONTACT PROCESS. The name is derived from the fact 
that by mere " contact " with a so-called catalytic material, 
the SO2 of burner gases and the oxygen of the residual air are 
caused to unite to form SO3, which is then either separated out 
by cooling (not usual) or absorbed in sulphuric acid of high 
strength, either maintaining the strength of this acid against the 
dilution by weaker acid (or water), or else increasing the strength 
of the absorbing acid above 100 per cent by the absorption of 
SO3 in H2SO4. When the acid arrives by absorbing SO3 at 
a strength at about 106 per cent, equivalent to 26.8 per cent per 
SO3 dissolved in H2SO4, absorption becomes slow. 

The word catalytic is something of a cloak for ignorance. 
Between the temperatures of 300° C. and 900° C. the 
mere presence of platinum in a finely divided state, or plat- 
inum black serves to very greatly accelerate the reaction SO2 
-f 0±=>S03- At first sight the platinum black appears to take 
no part in the reaction. It merely glows and gives off heat. 
The action starts about 325°, and is most complete between 400 
and 450°. Similar but less effective results are obtained at 
higher temperatures with ferric oxide, particularly ferric oxide 
containing a little copper oxide; also chromium oxide and even 
hot silica and quartz assist the rate of progress toward equilibrium. 
It may seem that none of these materials take part in the reac- 



82 ELEMENTS OF INDUSTRIAL CHEMISTRY 

tion, but probably each of them does in one way or another. 
Particularly is this the case with oxides of iron, copper, chromium 
and with the sulphates of alkalies and alkali earth metals. In 
the light of more recent knowledge, the original meaning of 
" catalytic " must therefore be abandoned or modified to the 
extent that a catalytic reaction may be defined as a reaction 
which leaves one of the assisting compounds substantially un- 
altered after the completion of the reaction. According to the 
law. of mass action such a catalyte or intermediate reacting 
compound is not to be expected to affect the ultimate equilibrium 
of the reaction, that is, the final extent to which the reaction 
proceeds in an infinite length of time. The function of the 
catalyte is merely to affect the rate at which the reaction pro- 
ceeds, and thus to give it sufficient rapidity to be of practical 
interest. Sulphur dioxide and oxygen unite to some extent 
(at a very slow rate at 350° to 375° C.) whether or not a catalyte 
be present. The presence of a suitable catalyte (possibly acting 
as a carrier of oxygen, similar in effect to the lower oxides in the 
chamber process) greatly increases the rate of reaction so that 
the sulphur dioxide and oxygen at 375 to 450° combine rapidly 
and produce sulphur trioxide with nearly theoretical complete- 
ness. 

Construction of Contact Plant. In order to illustrate 
the various principles used in the construction of contact plants, 
it would be necessary to describe a number of different plants 
more or less in detail provided actual installations were used to 
illustrate the principles. Instead of that a typical arrangement 
of the installation is given in Fig. 47, in the form of a schematic 
diagram which will be described in detail and which illustrates 
the principles used in the majority of the contact plants in this 
country. 

Air enters at the opening A into a drying tower B filled with 
quartz or other loose material down through which strong sul- 
phuric acid is flowing. The air passes up through this tower 
and on its way is almost completely dehydrated. It then passes 
down by the pipe B\ to the pyrites burners C into the cinder 
pit under which it is admitted by the pipes B2, B%, B4, etc. The 
doors of these burners C are of two kinds, upper and lower, the 
upper being for the insertion of the pyrites and the lower for the 
removal of the cinder. Both of these should be made as tight 
as possible by the use of asbestos gaskets and screw spiders 
or similar devices. Through the flue above these burners the 



SULPHURIC ACID 



83 



gases pass into a contact shaft D, where they pass over the cindei 
produced by the burners. This cinder is removed through the 
doors C-2 from the burners, is screened in order to remove dust 
and a portion of it is then put in through the funnel into the 
contact shaft D. About 10 per cent of the cinder is used to advan- 
tage in this way. The necessity for renewing the cinder arises 
through the accumulation of dust in the interstices and the fact 
that the cinder gradually becomes so saturated with arsenic 
and other impurities that it does not react promptly. The 
chief consideration, however, is the reduction of draft by stopping 




Fig. 47. 



up the interstices with dust. A portion of the cinder may then 
be shaken down into the cinder pit of the contact shaft 
and lemoved by the door Di. By the heat of the gases direct 
from the burners this contact shaft will be maintained at a 
temperature between 600 and 800° C. and in order not to have 
the temperature fall too low, the shaft is jacketed as well as pos- 
sible by somewhat heavy walls of brickwork and other devices. 
As the whole burner system and contact shaft operates under 
suction, it is preferable to enclose the entire setting in a steel 
plate cover closely riveted and calked. In this contact shaft 
the gases are partly converted, about 40 to 50 per cent of the SO2 
present when they leave the burner chambers being changed 



84 ELEMENTS OF INDUSTRIAL CHEMISTRY 

over into SO3, and sufficient heat being generated b}^ this reaction 
to maintain the temperature of the gases. Leaving the con- 
tact shaft by the pipe D3, the gases are somewhat cooled and are 
introduced into the cooling tower E. This tower consists af a 
riveted steel plate shell over the outside of which water is poured, 
the water being collected in a trough at the bottom and carried 
away. Some acid condenses in the pipe D3 and runs into the 
tower E. Also consideiable acid collects in the tower E and is 
removed by the pipes shown at the bottom. One such tower, 
unless of considerable size, would be insufficient to cool the gases 
so that they pass through the pipe Ei into a second tower E2 
(or third) of similar character, whence thoroughly cooled they 
pass by the pipe E3 into the absorbing tower F. This tower 
consists of either riveted steel plates or semi-steel castings, or 
cast iron poured into a mold containing a wrought-iron outer 
shell. The reason for this precaution is that cast iron is affected 
by SO3 in a peculiar way, the SO3 seeming to enter into the pores 
of the cast iron and cause a gradual expansion, placing the metal 
under such strain that it cracks or even bursts apart. The 
tower F is filled with quartz or similar surface-exposing material 
and is fed from above with a slow stream of acid for the purpose 
of absorbing the SO3 in the gas. From the tower F the gases 
pass on to the pipe F\ into the tower F2, which is of similar con- 
struction and likewise provided with a flow of acid, the strength 
and character of which will be mentioned later. Thence through 
the pipe ^3 the gases pass to the blower or actuating means for 
the system, the part of the apparatus hitherto described being 
operated under suction. From the blower the gases pass by the 
pipe H to a series of valved branches Hi, H2, Hz, etc., leading 
into filters I, I\, I2, etc. These filters are mere boxes of iron or 
lead containing a deep layer of fine coke, or fine slag from 
the basic open-hearth process. In either case the action is largely 
one of gaseous filtration, in order to remove the last suspended 
impurities that have not been taken out by the washing or the 
centrifugal action of the fan. This purification is so thorough 
that the gases no longer betray the presence of the dust in a 
strong beam of light nor do they yield up any impurity to filtra- 
tion by a close plug of cotton wool. If there be suspended sul- 
phuric acid left in the gases they will blacken the plug of cotton 
wool, or if any traces of dust remain these will be deposited 
upon the cotton and show their discoloration. The number 
of filters are thus placed in parallel in order to permit the cutting 



SULPHURIC ACID 85 

out of one filter by closing the entrance and exit valve and the 
renewing of the filtering body without interruption of the process. 
From these filters, the gases, thoroughly purified, pass away 
through the valved connecting pipes 1 3, 1 4, 1 5, etc., to the assem- 
bling gas main J. From here two courses are open to them, 
but the normal course used as a rule throughout the operation 
of the plant will be first described and the emergency course J\ 
described later. Normally the gases pass through J 2 downward 
through the valve K3 into the heat exchanger M . This heat 
exchanger is constructed very much like a tubular boiler having 
the tubes Mi connected between headers M2 and M3 and the 
incoming gases pass downward through these tubes and out 
of the heat- exchanger by the pipe M± up to the distributing 
main K. During the passage through the heat exchanger M 
they have been partially heated up by the hot gases passing away 
from the platinum converter R. They are again heated up by 
being passed down through the heat exchanger N of similar 
construction, having the pipes A r i between the headers N2 and 
N3 outside of which pipes are passing the hot gases from the 
first converter Q. The now thoroughly heated gases leave the 
heat exchanger N through the pipe iV"4 and pass upward into the 
pipe and downward through O2 into the converter Q. This 
converter consists of a cylindrical cast-iron box containing a 
number of layers of platinized asbestos supported on punched 
sheets of steel. The gases passing down through this platinized 
asbestos are further converted and heated by this action. They 
then pass away through the pipe Q2, and around the pipes Ni 
and are cooled by the incoming gases passing through the inside 
of these pipes. From this heat exchanger they pass through 
the pipe Q3 into the second platinum converter R, having similar 
layers of contact material Ri supported on steel trays. This 
converter may be somewhat larger in order to insure the complete 
conversion of the now nearly exhausted gases. From here they 
pass through the pipe R2 into the heat exchanger M, where they 
pass around the outside of the pipes and give up some of their 
heat to the incoming gases, passing down through the pipes. 
Leaving this heat exchanger through the pipe P3 they pass 
the final cooler S, which is again constructed somewhat like 
a boiler having headed pipes Si between the headers $2 and S3, 
only in this case instead of being cooled on the outside by gas 
these pipes are cooled by water fed through the pipe $4 and 
overflowing to the pipe S5. The now thoroughly cold gases pass 



86 ELEMENTS OF INDUSTBIAL CHEMISTEY 

through the pipe Sq into the absorbing tower T. This tower 
is filled with porous or other acid-proof material and is sprayed 
with acid from the distributer I2, after which the gases are per- 
mitted to exit through the pipe Ts to the atmosphere. 

The passage of the various liquids used for treatment of this 
gas should now be traced. The acid for absorbing sulphur 
trioxide from the iron conversion enters through the pipe a to 
the tank b at the foot of the tower F2, and adds itself to the 
liquid flowing down from the tower. Thence it flows to the pipe 
61 into the egg c, and is thrown up by the pipe c\ into the tank d 
at the head of the tower. The acid added by the pipe a should 
be of such strength and quantity as to maintain the flow of 
acid down the tower F2 somewhere between 93 and 99 per cent, 
preferably about 97 per cent, because the absorption of SO3 
is much more rapid and complete in sulphuric acid between 97 
and 98 per cent than in acid which is either much weaker 
or stronger. From the tank d most of acid is permitted to flow 
down the tower F2, but as the acid increases in quantity through 
the absorption of sulphur trioxide on the one hand and the 
addition of weaker acid from the pipe a on the other hand, the 
overflow goes to the supply tank e of the tower F, whence the 
acid trickles down in a slow stream through the tower F and may 
be raised to a strength equivalent to 105 or 106 per cent H2SO4, 
and be taken to the finished acid tank g. Calling the acid 105 per 
cent means that the sulphuric acid contains sufficient sulphur 
trioxide dissolved in it that, when the necessary water is added 
to unite with this sulphur trioxide and produce sulphuric acid, 
the total quantity of acid of 100 per cent produced will be 5 per 
cent greater than the amount of H2SO4 and SO3 taken. The 
strength may likewise, of course, be expressed by giving the per- 
centage of free SO3 dissolved in the H2SO4. The acid collected 
by condensation in the cooling towers E and E2 will be impure 
owing to the amount of dust carried over from the iron contact 
shaft and may profitably' be used in the preliminary drying 
tower B flowing down the pipes g$ and g± into the egg h whence 
it is blown up by the pipe hi into the tank i at the head of the 
drying tower. The excess of the drying acid thus accumulated 
may be flowed over to the pipe h 2 and utilized for any convenient 
purpose in the works. A deficiency of acid from these cooling 
towers is made up from the finished tank g by adding acid through 
the pipe g\. 

The absorption of the sulphur trioxide produced by the plati- 



SULPHURIC ACID 8? 

num contacts Q and R may be completely carried out in a single 
tower T provided the strength of the acid in this tower be main- 
tained at the most advantageous point between 97 and 98 per 
cent. A steady flow of weaker acid is taken in through the pipe 
j to the tank k, where it is cooled and thoroughly mixed with a 
stream flowing out through the pipe h from the tower. From a 
special compartment of this tank or an independent tank located 
beside it, &2, the acid is thrown up by a centrifugal pump or 
other convenient means by the pipe £4 into the supply tank I 
at the head of the tower, whence it flows through the pipe h to 
the distributer within the tower. A heavy stream of acid is 
carried in order that the sulphur trioxide absorbed may not too 
greatly increase the percentage of the acid on its way down the 
tower. Whatever excess of acid is formed in this system, as in 
the other, overflows to the tank k% and is regarded as finished 
acid. Owing to the careful preliminary purification of the gas 
this acid is very much purer than that produced by the iron 
contact. In some plants, therefore, the iron contact is not used 
and the gases pass directly from the burners into a large cooling 
chamber that takes the place of the towers E and E2, after which 
it is washed with sulphuric acid, as in the towers F and F2, which 
without the iron contact does not increase the volume of the 
supply liquid materially because there is no sulphur trioxide to 
speak of. By using stronger sulphuric acid in the tower F2 the 
gases are thoroughly dried and are prepared to go to the filters. 
The complete conversion is carried out in two steps in the con- 
verters Q and R and all of the sulphur trioxide produced is then 
absorbed in the tower T by 97 to 98 per cent acid. In such an 
installation the parts D, B, h and i would be omitted, as the pre- 
liminary purification of the gases has been shown to be more 
effective if the gases were moist. In fact moisture is injected 
into them as they leave the burners and before they are cooled 
in the laige chamber which according to that method of working 
would replace the cooling towers E and E2. 

In the other method of working the gases instead of passing 
through a more complicated conversion like that shown would be 
heated by exchange with the gases as they left the iron contact 
D, and would then be taken directly to a single platinum con- 
verter which might be located between two iron contact shafts 
or in any other convenient position for sustaining its temperature. 
The second stage of the absorption of the gases sulphur trioxide 
thus produced might, of course, be carried out in a second set of 



88 ELEMENTS OF INDUSTRIAL CHEMISTRY 

absorbing towers similar to F and F2. If a very complete con- 
version is to be made in the final platinum converter the tem- 
perature must be carefully regulated and provision made both 
for additional heating of the gases and reducing the amount of 
heating action. When it is necessary to increase the temperature 
of the gases passing through the first converter Q, as for instance 
in starting up of the plant, the heater P is available and provision 
is made through the valve 0\ and P2 for passing the gas through 
this heater into the pipe O2 by shutting the valve whenever this 
is desired. The heater P consists of an ordinary coal heater of 
special design provided with the firing door P3 and having inside 
heating pipes Pi and a stack for exit of the coal gases, Pq. When, 
on the other hand, it is desired to reduce the temperature of the 
gases passing through the first converter it is possible by opening 
the valve Ji to admit cold gases directly from the pipe J into the 
pipe L and thence into the converter. When a less violent cooling 
action is desired the valve K2 may be opened and the gas admitted 
to the pipe K before passing through the heat exchanger N. It 
will be obvious that the purpose of breaking up the conversion 
into a series of stages is to reduce the amount of heat liberated 
at any particular stage and avoid the necessity of cooling the 
gases during conversion. It amounts substantially to using a 
weaker gas at each stage in the conversion. Another method 
of getting at the same result is to make the converter Q very 
much wider and allow the radiation from the thin layer of con- 
tact material at the top to preheat the gases to such a degree 
that the contact mass itself is sufficiently cooled by radiation to 
the upper portion of the converter in which the gases are being 
heated. Another method of securing this result is to construct 
the converter like the heat exchangers N and M and to place the 
contact material within the tubes, passing the gases on their way 
to the contact around the outside of the tube so that the mass in 
the tube is continually kept cool by the passage of the gas around 
the outside. This was the method devised originally by Knietsch 
for maintaining within the contact chamber a temperature which 
at the hottest portion of the chamber should be between the com- 
posing and decomposing temperatures of sulphur trioxide. This 
most elegant form of contact chamber which combines within 
itself the converter proper, and the heat transferrer is illustrated 
in Fig. 48. The gases, after leaving the burners and being mixed 
with steam and cooled in a large cooling and settling chamber 
designed to take the place of the towers E and E2, Fig. 47, were 



SULPHURIC ACID 



89 



then washed as in towers F, F2, the washing being repeated in 
successive towers until the gases no longer showed any impurity. 
Special washing liquid might be used for different characters of 
special impurities depending on the kind of ore used and they 
were then finally dried in a tower like F2. Such gases were then 
passed directly in through the opening A, Fig. 48, whence they 
were permitted to circulate back and forth 
across the outside of the pipes B extending 
down through the chamber and finally 
reaching the bottom of this chamber to 
pass upward through these pipes themselves 
and to the contact material supported in 
layers within , these pipes. As the gases 
became heated on their way down to the 
end of the pipes and as the reaction at this 
entrance was more violent, the temperature 
at this point rose to the desired degree 
and the conversion proceeded very rapidly. 
Then as the gases passed on through the 
contact material contained in the pipes 
they would find cooler and cooler layers of 
contact materials so that their equilibrium 
might be retained at its most complete 
stage, at approximately 400 to 425°, before 
being removed from the pipes. In this manner 90 to 95 per cent 
or even 97 per cent of the SO2 may be converted in a single con- 
verter, and if desired, the temperature of the gases can be raised 
partly by an added exterior transferrer, through which the con- 
verted gases pass on their way to being finally cooled and absorbed. 
The final cooling may take place in a separate cooler, S } Fig. 47, 
or the absorption liquid may be so rapidly cooled that the hot 
gases can be cooled and absorbed simultaneously. If strong 
oleum is to be made, however, they should first be thoroughly 
cooled. If 98 per cent acid is to be made a single absorbing 
tower may be used, but if oleum is to be made it is more desirable 
to carry the absorption out in a series of towers, the last of which 
is supplied with 97 to 98 per cent acid in order to make an entirely 
complete absorption. 

Broadly speaking, it may be said that the cost of manu- 
facturing sulphuric acid by the contact system is not much, if 
any, higher than that by the chamber system. The operation 
i- somewhat more sensitive and delicate and involves the use 




Fig. 48. 



90 ELEMENTS OF INDUSTRIAL CHEMISTRY 

of more refined machinery, so that a higher class of labor has 
to be employed. The conversion when the contact system is 
operated properly is practically as complete as that in the cham- 
bers. Well designed, the contact system requires practically no 
fuel for preheating the gases and the power required for driving 
the gases through the more resistant series of chambers used in 
the contact system is more than made up by the absence of 
niter consumption. The cost of installation is somewhat higher 
owing to the considerable quantity of platinum used, hence the 
attempt to substitute other materials as oxide of iron, but it is 
doubtful whether in the long run the substitution works any 
economy. One advantage of the contact system, particularly 
where platinum alone is used, is the great purity of acid resulting 
from the necessary thorough purification of the gases, but for 
ordinary manufacture of sulphuric acid, particularly in districts 
more or less remote from foundry and machine shop facilities, 
there is considerable question whether the contact system offers 
great inducement to the manufacturer. 



CHAPTER V 
NITRIC ACID 

PROPERTIES. Strong nitric acid when free from lower 
oxides and freshly made is practically colorless, but the action 
of light, slightly elevated temperatures, or traces of organic 
matter, generally gives it a slight pale amber tint gradually 
developing into* a clear pale red-brown. It is more mobile than 
sulphuric acid of like strength and about one-third lighter in 
weight. Pure acid of 99.5 per cent reaches a specific gravity 
of 1.52 (49.6° Be.). Unlike sulphuric acid, the anhydride is not 
stable in solution in the acid (unless H2SO4 is present), so strengths 
higher than 100 per cent are not made, but N2O4 dissolved in 
the acid increases its specific gravity until 12 per cent of N2O4 has a 
density of 1.62 (about 56° Be.), and shows a greater oxidizing 
power than the pure acid. 

The destructive action of nitric acid on organic matter is 
rapid, partly oxidizing and partly nitrating (forming nitric esters 
or NO2 substitutions). The oxygen-containing bodies of the 
paraffine series tend to form oxalic acid, the — CHOH groups to 
form esters, a characteristic also exhibited by cellulose, glycerine 
and under proper conditions, starch. The sulphur-containing 
bodies tend to sulphonic acids, while the aromatic series is char- 
acterized by its greater tendency to form nitro derivatives. Most 
ordinary metals are attacked by nitric acid of various strengths, 
gold and platinum excepted. The hydrogen liberated acts upon 
the nitric acid to reduce an additional portion of it, liberating 
various oxides of nitrogen, depending on the concentration of 
the acid and the temperature. Broadly speaking the more con- 
centrated the acid the more higher oxides will be produced and 
dilute acid will be largely reduced to ammonia. Lead and 
iron, however, are somewhat slowly acted upon by strong acid, 
iron in particular being the material generally used for the dis- 
tilling parts of nitric acid apparatus. Its protection at this 
point is due to three causes, chiefly the presence of sulphuric 
acid, superseding or inhibiting the action of the nitric and form- 
ing insoluble sulphates which orotect the surface; second, the high 

91 



92 ELEMENTS OF INDUSTRIAL CHEMISTRY 

temperature which prevents condensation of acid on the surface, 
and lastly to some extent the peculiar passivizing action which 
nitric acid possesses for iron surfaces. 

OCCURRENCE. The usual commercial strengths of nitric 
acid are " 38° " (56.5 per cent), " 40° " (61.4 percent), and 
" 48° " (91.4 per cent). " Pale acid," " free from lower oxides " 
(that is, less than 0.1 per cent of NO, N2O3 and N2O4) may be 
of any strength, but is generally made from acid stronger than 
40° Be. (sp. gr. 1.381) by dilution because the weaker acid does 
not " bleach " well. " Red acid " is generally 40° Be. or 
stronger and contains dissolved lower oxides. " Dynamite 
acid " is strong acid for making 96 per cent mixed acid (34 per 
cent HNO3 and 62 per cent H2SO4). It was formerly necessary 
to have the nitric acid 93 per cent, but now that " oleum " is 
used, it need only be 88 per cent. " Spent acid " is the mixed 
acid diluted and partly deprived of HNO3 by use in nitrating 
organic substances; and " fuming nitric " is very strong acid 
containing much lower oxides. " Weak nitric," generally 
applied to acid 38° Be. or less, obtained from the final towers or 
tourilles of the condensing system, is also frequently called 
" tower acid," particularly when used to supply the Glover tower 
of a chamber system. " Aqua fortis " or " strong water " 
(because of its great solvent power) is the name given nitric 
acid by Geber (a.d 750-800), or one of his immediate prodeces- 
sors, who made it by heating together saltpeter, copper vitriol and 
alum. The first mention of the present process of making it is 
by Basil Valentine (a.d. 1450-1500) who says, however, that 
this method had long been used. Nitric acid was, therefore, 
one of the earliest mineral acids known. 

MANUFACTURE. In this country Carter & Scattergood of 
Philadelphia began the manufacture of nitric acid in 1824 but 
the industry was not very important until 1862, when the dis- 
covery of nitroglycerine, followed by other nitro-explosives, 
opened a new field for it. 

Two general methods of making nitric acid are important, 
first, the old reaction of Basil Valentine from nitrate of soda 
(natural deposits) by action of an excess of sulphuric acid and 
distillation of the liberated nitric acid, the reaction approximating 

NaN0 3 +H 2 S04 = NaHS04+HN0 3 . 

The second method is synthetic and developed from Sir Wm. 
Crookes's fascinating suggestion in 1890, that the ultimate exhaus- 



NITRIC ACID 93 

tion of the natural deposits should be anticipated by perfecting 
the combustion of air, giving a practically inexhaustible source 
of nitrogen products for fertilizers. This modern process consists 
in burning the nitrogen of the air with its oxygen in an elongated 
electric arc and quickly cooling the resulting gases. It is only 
within the last five years that it has developed commercially — 
principally in Norway, Sweden and Switzerland because of the 
cheap water power available there. Mixed oxides of nitrogen are 
thus produced and their oxidation completed in reaction towers 
after which they are absorbed in milk of lime. The acid neutralized 
produces " nitro-lime," chiefly used for fertilizer. It is question- 
able whether the production of strong nitric by this process can 
be carried out economically except when extremely cheap electric 
power (from waterfalls) is available. In this country one com- 
mercial failure was made during the early stages of the develop- 
ment of this process, but another installation is practically com- 
pleted and under much more favorable auspices promises 
better results. Weak nitric acid increases in strength on dis- 
tillation until 69 per cent is reached, after which a hydrate 
(2HX0 3 -3H 2 0) of about 70 per cent HNQ 3 distills over at 
a constant boiling-point. Some methods of overcoming this 
difficulty and making the synthetic process directly available for 
the production of strong acid, have been proposed but com- 
mercial success has not yet been attained. 

The practical processes, then, make nitric by treatment of 
sodium nitrate with sulphuric acid. Four methods of decom- 
posing have been claimed as successful, those of Prentice, Uebel, 
Yalentiner and the various forms of plain still (most generally 
used in this country). 

Prentice Process. This method consists in continuously mix- 
ing the nitrate and an unusually large excess of sulphuric acid 
in a separate vessel provided with a condenser to which the 
X2O4 and CI liberated are supposed to pass, leaving the nitric 
to be distilled off free from these impurities. It was said to have 
worked for some time satisfactorily at Stowmarket, England, 
and to be capable of producing its entire output at a strength 
of 94 per cent. The feature apparently most criticised was that 
12 parts of oil of vitriol were required for 10 of nitrate of soda, 
but this is no more than should be used to get a good niter cake 
containing 30 per cent free acid, easy to fuse and fluently mixing. 
A very slight loss of nitric, at 4 J cents per pound, quickly makes up 
for any saving in sulphuric, at half a cent per pound. The acid 



94 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



then made was not what we would regard as well bleached but this 
could easily have been remedied. 

Uebel's Process. In this system, Fig. 49, half of the niter 
cake (approximately NaHSC>4, which results after expelling the 
last nitric acid from a charge in retort A) is to run into an equiva- 
lent weight of moderately strong sulphuric acid in the pan B lo- 
cated over the flue C. In this pan the heat of the niter cake serves 
to drive out 15 or 20 per cent of water from the sulphuric acid, 
and form practically anhydrous " poly sulphate " NaH3(SQi)2- 




This is maintained in a fused condition by the heat of the flue 
C below, retained by the cover D, and is drawn off by the valved 
pipe E and the gutter F into a hoisting pot G that can be elevated 
by chain fall or power hoist and by trolley rail carried over the 
feed hole of the retort H or H'. These are charged alternately, 
at intervals of about 4 hours, with 700 to 900 lbs. of nitrate of 
soda, dried by spreading out in the iron pans J. Charging is 
done through the feed hole K, which is then closed with a stone 
or stoneware plate L and covered with nitrate of soda. Some- 
times the hoisting pot is provided with a bottom nipple (fitting a 



NITRIC ACID 



95 



small hole in the plate L) closed inside with a plug valve. Some- 
times the fused " polysulphate " is poured in. Particularly in 
the latter case it must be added slowly, as the hot liquid liberates 
considerable nitric acid as vapor. To avoid unnecessary heating 
at this stage the damper M is closed, all the fire being given to 
the retort H', which is then being boiled off. When the polysul- 
phate is all in (about 4 minutes) the damper M is opened and 
the boiling off of H is begun, which occupies from 2 to 3 hours. 
During this time boiling off of H' is completed, the damper M' 
is closed and by opening the valve the liquid bisulphate in H' 
is run down to the lower retort A. The retort A is never wholly 
emptied (except in shutting down) so that the incoming bisulphate 




Fig. 50. 



blends with the already highly heated charge and thus gives up 
the last of its nitric acid. The now empty retort H' is then 
( usually after slight cooling) charged with its nitrate of soda and 
a fresh hoisting pot of liquid polysulphate. As a matter of fact, 
however, Uebel's retorts are generally operated with sulphuric 
instead of polysulphates. 

Valentiner Process. By this method the nitrate is decom- 
posed under a vacuum. At first the suction was commenced as soon 
as the charge was made and increased until about one-third of an 
atmosphere remained, when the heat was applied. It was found, 
however, that the intimate mixture of nitrate and acid was better 
insured, and frothing which carried suspended nitrate upon the 
sides of the retort, was prevented by throttling the outlet of the 
gases. About 2200 lbs. of nitrate is charged into the retort A, 



96 ELEMENTS OP INDUSTRIAL CHEMISTRY 

Fig. 50, through the hole B having an iron lid, which is then care- 
fully diluted. Sulphuric acid (2360 lbs. 66° o. v. or preferably 
96 per cent) is then run in from a measuring tank or scale tank 
C by a pipe D goosenecked and provided with a cock. When the 
acid is all in, suction is applied by the means of the 12X16 inch, 
60 r.p.m. vacuum pump E. This is protected from the acid 
fumes and chlorine liberated from any NaCl in the niter by a 
series of wash bottles alternately empty and about half filled 
with milk of lime. Pipes may be arranged as indicated to insure 
against either sucking back or absence of liquid in its proper 
wash bottle when operating. Under the suction and heat of 
reaction rapid evolution of nitric vapor begins. To prevent its 
becoming too rapid a throttle plate with a small hole is inserted 
between the still and the gas pipe G, which is provided with a 
Y-branch for cleaning and is surmounted by a short length of 
wire-covered glass pipe H for observing the color of the passing 
vapors. A reducer pipe to 2\ ins. then takes the gases to a small 
tourille / filled with broken pumice, where entrained sulphuric 
or niter dust are separated. Thence the gases pass through two 
large stoneware coils J and K (2 J ins. bore and about 45 sq. ft. 
cooling surface), placed in wooden tanks supplied with cold water 
at the bottoms and provided with overflows near the tops. Here 
the acid is largely condensed and most of it flows into the large 
receiver P. Wire-covered glass pipes L and M are provided at 
the outlet of each coil for observing the color and rate of flow of 
the acid and a device N for drawing samples for testing. A three- 
way cock is provided to pass any weak or discolored acid into 
the smaller jar S, the flow to which can be observed at R. Any 
air or uncondensed vapor from the coils passes through the pipe 
Q and the jars S and T, where it deposits some acid, and then 
upward through the reflux cooling worm V, 2\ ins. bore about 
22 sq. ft. cooling surface, where nearly all the condensible vapor 
is caught and returned to the jar T. Weaker acid collected in 
S and T may be added to the 96 or 98 per cent sulphuric used for 
charging the retort. Bleaching of the acid is not required in this 
process for two reasons : the solution pressure of N2O4 and CI in the 
acid is greatly reduced by the vacuum, and also the low temperature 
of vacuum distillation causes very little breaking up of the nitric 
to form N2O4. The slight loss corresponding to the HC1 liberated 
and oxidized to nitrosyl chloride at the expense of nitric is inevi- 
table. No loss by leakage of joints can occur under suction and 
less breakage of stoneware results from the lower temperatures 



NITRIC ACID 



97 



employed. More continuous rapid evolution of vapor makes it 
possible to run off the charges in about eight-hour cycles. After 
the first application of two-thirds of an atmosphere suction it 
gradually increases as evolution of vapor begins to reduce the 
temperature in the retort. Heat is then gently applied until the 
retort reaches 80° and, as the rate of vapor evolution again 
decreases, is gradually raised to 130°. When the acid flow ceases 
the pump is shut off and the heat raised to facilitate running of 
the niter cake through the bottom spout W. An excellent quality 
of acid (XoO3 = .05 per cent) is produced, about 80 per cent 
averaging 96 per cent HNO3, or the whole output averaging 89 
per cent if weak acid is returned with the sulphuric to the retort. 
The niter cake produced is of excellent quality. The statements 
found in the literature that " perfectly pure nitric monohydrate 




. 



iif k^^^ 




Fig. 51. 



1HXO3) produced by this process is now found in commerce," 
is, however, an exaggeration, although the writer regards the 
process as one of the best on the market to-day. 

Common Process. By far the greater proportion of nitric 
acid, however, is made by the simple action of sulphuric acid on 
the nitrate of soda at substantially atmospheric pressure. This 
reaction is generally carried out in ordinary cast-iron retorts 
either of cylindrical pattern horizontally placed, or of the general 
shape of deep pots. The former is illustrated in Fig. 51, in which 
A is the brick setting properly provided with buckstays B. 
Through this setting extend cast-iron cylinders C provided at 
either end with a closing plate D consisting of either cut stone 
or cast iron. One of these plates, generally the one above the firing 
door, is provided with two holes. The smaller hole E serves for 
the introduction of the acid and the larger hole F for the charging 
with nitrate of soda, after which it is closed either by a luted 



98 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



cover or by a screw plate. The plate on the opposite end is 
provided with holes G into which the exit pipe for gases is luted 
and H for tapping off niter cake. These cylinders vary from 
3 ft. in diameter, 5 ft. in length, to 5 ft. in diameter and 10 ft. in 
length, sometimes the diameter being as great as 5 ft. 6 ins. The 
charges of nitrate of soda are 700 to 2200 lbs. It will be noted 
that a relatively small grate area and a single fire is used and much 
of the success of the operation in yield, quality and speed depends 
on its careful manipulation. According to the older practice only 
a slight excess of sulphuric acid was used and the niter cake remain- 
ing behind was consequently so hard that it was necessary to 
get into the still and dig it out. Modern practice, which to a 
very large extent utilizes the niter cake for other manufacture, 
permits 33 to 36 per cent excess of sulphuric to remain in the 




Fig. 52. 



Fig. 53. 



niter cake. The end plate, generally that in the rear, is pro- 
vided with a hole at the bottom for withdrawing the niter cake, 
this hole generally being closed by an iron peg or tap loosely 
ground in and sometimes held in place by a screw handle. 

Pot Still. Another form of still, pot-shaped in general 
outline, is shown in Fig. 52. The bottom, middle section and 
cover being cast in separate pieces to permit of separate renewal 
according to the wear which they have suffered. The belt and 
top are generally lined with brick as indicated in Fig. 53. The 
bottom piece is left unlined to permit the free transmission of 
heat and because the corrosion at this point, where there is always 
plenty of sulphuric, is very much less. The bottom of this pot 
is provided with a hole F set in a trough G, thus permitting the 
bi sulphate, when the charge is completed, to be run out into a 
pan or wagon. The gas outlet H, 3 to 6 ins. in diameter, and the 
charging hole I, 8 to 10 ins. diameter, are provided in the cover. 



NITRIC ACID 99 

These sections are luted together with acid-proof cement, for 
which purpose " Vitrex " cement may well be used; or cement 
made up at the works from asbestos powder containing a little 
finely powdered barium sulphate, made into a thick paste with 
5 per cent silicate of soda solution; or equal parts iron filings and 
powdered brimstone, thoroughly mixed with 4 parts of ground 
firebrick with as little water as will serve to make a thick putty. 

Charging. After completing one charge and before putting 
in another, the retorts are allowed to cool somewhat, as the hottest 
part of the operation is at the end, which temperature would be 
too high for initiating a new charge. The nitrate of soda charge 
is then dumped into the still, generally after drying if strong acid 
is required. The manhole plate is luted or clamped on and the 
sulphuric acid run in rapidly. Evolution of nitric begins before 
all the sulphuric acid has been added, but a light fire is started 
before the evolution slackens and the heat is gradually increased 
so as to ensure a steady flow of nitric acid. A single charge of 
2200 lbs. is generally run off in one of these large size retorts in 
2-4 hours, though by skillful manipulation it is possible to secure 
two charges in 2-i hours or at most, 27 hours. In many factories, 
however, it is found most satisfactory to have the still started 
in the morning, under the eye of the superintendent, and have 
no charging done at night. 

Distillation. The first run of the acid is generally weak, 
or impure or both. It is the writer's experience that to some 
extent this depends on the character of nitrate used and the 
strength of the sulphuric acid applied. Nitrates containing 
chloride will produce impure acid to begin with because of its 
contamination with nitrosyl chloride. If the charges are made 
in too hot a still or if the sulphuric acid is run in too rapidly, 
there will be considerable lower oxides in the first run of acid. 
Likewise, if impure nitric, recovered from the final towers of the 
condensation system, has been mixed with the sulphuric used 
for charging, most of its impurities will come over in the early 
stages of the reaction. The retort should not be too cold at the 
time of charging or the partial condensation of nitric acid on its 
surface will cause excessive corrosion with contamination of 
niter cake and early destruction of the still. The whole retort 
should be as nearly as possible the same temperature throughout ; 
therefore it is desirable to have the retort enclosed as completely 
as possible in the brickwork. This temperature should be very 
slightly above the boiling point of the nitric acid, enough above> 



100 ELEMENTS OF INDUSTRIAL CHEMISTRY 

however, materially to warm up the charge of niter when added. 
The nitrate of soda is perferably dried and sulphuric acid used 
at approximately 93 to 95 per cent, or equivalent strength of 
H2SO4 after diluting with recovered nitric. Too strong sulphuric 
is apt to promote the formation of lower oxides by dehydration 
of the nitric acid. Too early an application of the fire or too rapid 
introduction of the sulphuric, or too high a temperature of the 
still are all apt to produce irregular and incomplete mixing of 
the* charge by distilling out too much nitric in the initial stage 
of the operation. When all conditions are right, a gradual and 
steady distillation should begin when about one-third of the 
sulphuric acid has been introduced and should only reach its 
full strength just after the last of the sulphuric has been added. 

Condensation. There are two general methods of carrying 
out the condensation of nitric acid. In the older method the 
condensed acid brings down with it such lower oxides and chlorine 
as it may carry and the product is separated into stronger or 
weaker fractions according to the requirements of the market 
and the uses to which it is to be put in the plant. This system 
is naturally best adapted to the production of extremely high 
strength acid, because of the separation of various fractions. 
It is necessary, however, to treat the acid thus produced in order 
to purify it. This is done by heating the acid and blowing out 
the impurities with dry air. Some of the high strength secured 
is lost because of the tendency of the strong nitric to distill out 
of the mixture. The other method consists in treating the dis- 
tillates from the still on the reflux condenser principle and making 
the heated gases, sometimes mixed with a little air, coming from 
the still serve the purpose of bleaching the acid, thereby produc- 
ing substantially the entire output of the still at a somewhat 
lower percentage, but all of highly bleached and purified quality 
so far as lower oxides and chlorine are concerned. Other systems 
of condensation combine, to a greater or less degree, the two 
different characteristics above outlined. Two such systems will 
be described; in the first instance to show the extreme of con- 
densation and subsequent purification and in the last to show 
the extreme of complete production and automatic bleaching 
by the action of the hot gases. 

Fig. 54 illustrates the condensing plant designed to operate 
under the first mentioned systems, i.e., collection and subsequent 
purification of the acid. The distillate from still A passes over 
into a first receiver B designed to catch any impurities carried 



NITRIC ACID 



101 



over by foaming or excessive violence of distillation. The 
acid in this receiver is, however, under normal conditions, clear, 
and pure enough for use along with the major portion of the pro- 
duction. Provision is therefore made for carrying this acid down 
by the pipes C and the gutters D to the general receiving reservoir 
after it has been examined and proved satisfactory for use. The 
greater portion of the gas, however, passes up through the pipe F 
and is condensed in coils G surrounded by water in a wooden 
tank, whence the condensed acid flows along with the uncondensed 
remainder of gas into the receivers H. Herein collects the greater 
portion of the condensed acid and it is not unusual to provide 




Fig. 54. 



a pair of receivers in the position H, one intended for strong and 
the other for weak acid. In the pipe between G and H is pro- 
vided a three-waj r cock so that the acid according to its strength 
may be separated into one or other of the receivers. Two reser- 
voirs E are provided for receiving the acid respectively from the 
two receivers H, whether it be strong or weak. After leaving the 
receiver H the gases pass over into a second receiver I, wherein 
the residual portion of suspended liquid may be collected, as 
also the return drips from the gas pipes leading into the recovery 
towers K and L. This gas line is provided with branches J' 
to bring the gases from the receiving tank M into which strong 
acid is blown from the receiver E when it is desired to bleach the 



102. ELEMENTS OF INDUSTRIAL CHEMISTRY 

acid; also the branch J" from the receiver E to carry off any 
unoxidized gases that may be generated in that receiver and the 
branch J"' from the receiver at the top of the tower into which 
the stronger spraying acid is blown. The two towers K and L 
are connected in series, packed with coke and provided with an 
outlet N connected with a chimney or other source of draft. 
In these towers the lower oxides of nitrogen are absorbed in respec- 
tively stronger nitric in the tower K and water in the tower L 
and^ oxidized by the air which comes through the system along 
with these gases from various leakages, etc. The weak liquid 
going down the tower L passes through the pipe I into the receiver 
V, whence it goes into an air lift I" and is thrown up thereby into 
the storage tank P at the top of the other set of towers. From 
here a pipe p permits the exit of the air used in blowing to the 
atmosphere because the acid in this tower is so weak that little 
gas will be carried away from it. From the tank P a pipe returns 
the weak acid to the top of the tower L, which contains a distrib- 
uter to insure equal flow of acid down through the cross-section 
of the tower. The receiver U receives a slight but steady flow 
of water maintaining the acid in the system of the tower L at 
about 18° to 20° Be. Naturally with the addition of water 
absorption of gas and oxidizing of this gas into nitric acid, an 
excess of acid accumulates in the tank P. This excess is permitted 
to overflow by gravity to the pipe p' into the strong acid receiver 0, 
from the bottom of which a supply pipe is carried to the tower 
K. , From the bottom of this tower K a pipe k carries the strong 
tower acid into the receiver k', whence it passes into the air- 
lift ~k" and is elevated into the receiver 0. In this tower the 
stronger gas is absorbed and oxidized and a portion of the outflow 
from the tower K is permitted to pass out through the valve q 
into the receiver Q for the recovered tower acid, which will be 
from 35 to 40° Be. The strong acid accumulated in the receiver 
E is elevated by a Montejus or air lift, not shown, into the receiver 
M, which is the acid supply reservoir for the bleaching system. 
From here it is allowed to flow in a slow stream through the coil 
R immersed in a hot water tank and thence into the tower S, 
wljich is likewise immersed in a deeper hot water tank and is 
filled with pumice stone or coke. The temperature of the hot 
water in the two tanks is carefully regulated to heat the acid to 
approximately 80° C. and a slow stream of air is supplied to the 
bottom of the tower S through pipes not shown. The acid warmed 
up in the coil R and flowing down over the extended surface of 



NITRIC ACID 103 

the coke or pumice in the tower S is fully exposed to this stream 
of warm air and thus oxidized. At the same time whatever 
Lower oxides of nitrogen not thus oxidized are blown out by the 
stream of air and with it into the coil above. 

This coil is connected as a reflux and is given a very small 
supply of water, since the object is only to condense the liquid 
which might be carried out with the gas. The lower oxides 
pass out through the coil T into the strong tower U of a separate 
recovery system, where they are oxidized, as were the lower 
oxides, from the generating plant in the tower K. Likewise a 
second tower B for weak acid is provided similar to the tower L. 
The supply of acid for U is taken from the reservoir 0, which sup- 
plies the other strong tower K, and the weak acid for supplying the 
tower V is taken from the reservoir P. The outflow lines at the 
bottom of the towers U and V respectively join the lines k and 
/ respectively from the strong and weak recovery towers connected 
with the generating system and the same air lifts furnish a con- 
tinuous supply for both the decomposing and the bleaching 
system. After passing down through the heated tower S the 
acid is entirely freed from chlorine, contains less than 0.10 per 
cent lower oxides figured as N2O3 and is received in the jar W 
for test and examination, whence it is run by a pipe not shown 
into the final receiver for bleached acid X. This system will 
seem to be somewhat complicated, but it is found to be thor- 
oughly efficient and lends itself readily to careful control to the 
quality of acid at various points. Some of the larger manufac- 
turers of strong nitric, for use in making mixed acid, both in this 
country and abroad, use this system with great success. 

Skoglund Condenser. In most nitric acid plants the 
aim is to combine the condensation and bleaching into a single 
step, by doing the condensation at such a temperature that as little 
of the lower oxides of nitrogen shall be condensed with the acid 
as passible and that in the second place what little is condensed 
shall be supplied with sufficient hot air to carry out its oxidation 
at once and produce in a single step a water-white acid of high 
strength. The simplest, and in the writer's opinion the most 
efficient apparatus for this purpose is the condenser system of 
Skoglund, see Fig. 55. It is characterized by the carrying out 
of this preliminary condensation and bleaching action in a tower 
somewhat similar to, though smaller in size, than the final towers 
used for the oxidation of lower oxides that cannot be condensed. 
From the still A the gases pass over in the usual manner into a 



104 



ELEMENTS OF INDUSTRIAL CHEMISTRY 




Fig. 55. 



tourille or jar B, serving as a sort of safety bottle to catch any 
suspended matter that may be carried over when the still foams. 
From here they pass through a pipe C into a special injector 
pipe D, which is arranged to be served with compressed air and 

thence into the bottom of 
the tower F. This tower 
is filled with lumps of 
quartz, through which the 
hot gases mixed with air 
pass upward, while the acid, 
after condensation, flows 
downward. From the top 
of the tower the gases pass 
through a condenser, which 
is generally a water-cooled 
coil. In this figure it is 
shown as an air-cooled 
series of pipes G, which 
may, however, be water 
cooled if desired by covering 
each with a piece of linen 
and trickling water down upon them from above. The purpose 
of the linen is to distribute the film of water equally over the 
surface of the pipes and not permit it to flow through certain 
lines caused by salt deposits, thus producing irregular cooling 
and consequent breakage of the pipes. From this condenser 
the gases pass over by a pipe F to the bottom of the tower H and 
thence through the tower H', both of which are similar to the 
final towers in either of the other systems described. The acid 
produced in the condenser G flows downward through the tower, 
entering it at almost the boiling point, which temperature is 
maintained throughout its entire flow over the surface of the 
quartz. Accumulating at the bottom of the tower, the acid 
then flows out through the pipe I into the small jar or tourille J, 
whence it flows through the cooling worm K, out of the top of this 
worm through the overflow L and into the final storage jar M. 
Similar storage jars are provided for the acid from the towers 
G and H so that it may be returned with the sulphuric acid into 
the still A. Through the center mouthpiece of the jar J another 
hot-air pipe is carried to the bottom of the acid in J and the large 
mouthpiece of J is connected with a similar inlet to the tower so 
that instead of using the injector through the pipe D air is pref- 



NITRIC ACID 105 

erably blown through the hot acid collected in the jar J and the 
gases thus removed carried back into the tower. In order to 
maintain this tower at a high temperature it is customary to 
connect three or four stills charged in rotation to a single tower. 
Either the bottom of the tower is provided with inlets on three or 
four sides, or else a common gas main is employed, into which 
the injectors are connected. The jar B is asbestos-covered 
but it cools down considerably after each charge and serves as 
a sort of preliminary condenser to catch the first weaker acid 
that comes over when the still is charged. In some cases this 
acid is added to the condenser acid at the top of the tower by 
means of a specially provided neck, but generally it is mixed 
with the sulphuric acid and the weaker acid from the final towers 
H and H', the whole being returned to the still with the nitrated 
soda of the succeeding charge. Using moderately dry (not spe- 
cially dried) nitrate of soda and 98 or 99 per cent sulphuric diluted 
with the weak nitric acid to a strength of approximately 93 per 
cent H2SO4, the average output from this plant is from 89 to 
90 per cent in strength, perfectly water-white and substantially 
free from chlorine. The operation is conducted under a slight 
suction. As the tower E is carefully jacketed with insulating 
material so as to maintain its high temperature and protect it 
from contact with the cold air, and the pipes C and D are also 
carefully jacketed, there is practically no risk of breakage except 
of the air-cooled pipes G. This breakage is as small as can be 
credited to any form of nitric condensation. 



CHAPTER VI 
ELEMENTS AND INORGANIC COMPOUNDS 

ALUMINIUM. This is one of the most important of the ele- 
ments. It occurs in nature in the form of hydrated oxides such 
as bauxite, diaspore, and hydrargillite; and as silicate such as 
common clay, kaolin, feldspar, and cryolite. It was first prepared 
in a free state by Wohler in 1827, who heated to redness a mixture 
of aluminium chloride and metallic potassium. Many attempts 
were made to produce the metal electrolytically, but the processes 
were not successful in America until 1890, when Hall took out 
his patents on the electrolysis of fused alumina in the presence 
of a fluoride. 

Aluminium is a silvery white metal having a specific gravity 
of 2.7. Its lightness and resistance to atmospheric influences 
have brought it into use for a variety of purposes where great 
strength and low weight are desirable. One of its important 
applications is in the manufacture of thermite, a material consist- 
ing of a mixture of iron oxide and powdered aluminium. This 
mixtuie when ignited produces a very intense heat, causes a 
reduction of the iron oxide and is applied in the welding of steel 
and in foundry processes. Alloyed with other metals aluminium 
gives a very valuable series of bronzes. 

ALUMINIUM OXIDE. The oxide of aluminium is of commer- 
cial importance in the form of corundum, emery, ruby, and 
sapphire, as well as a raw material for making metallic aluminium. 

ALUMINIUM ACETATE. This compound usually is found on 
the market in a liquid condition known as " red liquor." It may 
be prepared either by acting upon aluminium hydroxide with 
acetic acid, or by double decomposition of aluminium sulphate 
with calcium acetate. It is principally used as a mordant in 
dyeing and printing and in the water-proofing of tissues. 

ALUMINIUM CHLORIDE. This compound is prepared by 
passing dry hydrochloric acid gas over heated metallic aluminium, 
or by heating a mixture of aluminium oxide and carbon in the 
presence of chlorine. The chloride distills off as a white crystal- 

106 



ELEMENTS AND INORGANIC COMPOUNDS 107 

line mass, which fumes in the air and boils at 183° C. Its princi- 
pal use is in the manufacture of organic compounds by the Friedel 
and Craft reaction. Its acid solution is sometimes used as a 
disinfectant. 

Aluminium Hydroxide. This product is obtained as a 
gelatinous precipitate on treating salts of aluminium with alka- 
line hydroxides or carbonates. On a commercial scale it is 
usually prepared by the Lowig process, which consists in treat- 
ing sodium aluminate with milk of lime. By this process sodium 
hydroxide and calcium aluminate are produced. The calcium 
aluminate is then dissolved in hydrochloric acid and to the alumin- 
ium so formed is added a calculated amount of the calcium 
aluminate. As, a result aluminium hydroxide is completely 
precipitated. The freshly prepared aluminium hydroxide is 
employed to precipitate many of the dyestuffs from their solu- 
tions, thus forming insoluble colors known as lakes. 

ALUMINIUM NITRIDE. Recently a new carrier of nitrogen 
has attracted a great deal of attention. If alumina is heated 
with carbon in the presence of nitrogen to about 1900° 
C.j A1X is formed. This nitride when treated in an autoclave 
with caustic soda forms sodium aluminate and ammonia, serving 
both as a means of obtaining a pure alumina for the aluminium 
industry and for the fixation of nitrogen. Unfortunately the 
difficulty of obtaining furnaces of the required life are so great 
as to preclude any present successful solution of this process of 
fixing nitrogen, though much effort and money is being expended 
in the attempt. 

Aluminium Sulphate. The sulphate of aluminium 
AI2 >04^3. I8H2O is prepared from clay, bauxite or from the 
aluminium oxide obtained in the manufacture of soda by the 
cryolite process. The calcined clay is finely pulverized and 
treated with sulphuric acid (sp.gr. 1.47). The mixture is heated 
to start the reaction, which soon becomes violent. At the end 
of the reaction a hard cake remains (alum cake), which contains 
the silica, iron and other impurities. From bauxite, it is pre- 
pared by adding enough sodium carbonate to the finely powdered 
mineral to form a mixture containing 1.2 molecules of sodium 
carbonate for every molecule of aluminium oxide. The mass, 
after fusion, is rapidly lixiviated and the solution of sodium 
aluminate thus obtained is filtered, concentrated to 35° Be. 
and treated with a current of carbon dioxide which precipitates 
the AI2O3 in a granular form. This precipitated oxide on dissolv- 



108 ELEMENTS OF INDUSTRIAL CHEMISTRY 

ing in sulphuric acid produces a sulphate which contains not over 
.02 per cent of Fe2C>3. 

The aluminium oxide obtained in the cryolite process when 
dissolved in sulphuric acid produces a very pure form of aluminium 
sulphate. 

ALUM. Alums have the general formula M /// 2 (S0 4 ) 3 , 
M , 2S0 4 24H 2 0. 

POTASH ALUM. Potassium aluminium sulphate, A1 2 (S04)3, 
K2SO4, 24H 2 0, is obtained from alunite or alumstone, which is 
mostly found near Rome. The mineral is calcined at a moderate 
heat (about 500° C), exposed, when moist, to the atmosphere 
for 3 or 4 mouths, and then lixiviated. The alum obtained by 
the evaporation of the wash waters contains a small amount 
of basic aluminium sulphate and crystallizes in cubes called 
Roman or cubical alum. 

Alum may be obtained from alum schists or slates by roasting 
and subsequent exposure to the air. The iron sulphide present 
is oxidized to sulphate and sulphuric acid. This latter reacts 
on the aluminium silicate, forming sulphate of aluminium. The 
ferric sulphate formed attacks the aluminium compounds, pro- 
ducing aluminium sulphate and basic ferric sulphate. The 
mass is washed and the solution evaporated to 40° Be. Most 
of the iron compounds crystallize out, and are separated. The 
proper amount of potassium sulphate in concentrated solution 
is now added when the alum begins to separate. The crystalline 
product obtained still contains some iron and must be purified 
by recrystallization. 

Alum may be readily obtained b}^ adding the proper amount 
of potassium sulphate to a concentrated solution of aluminium 
sulphate and allowing it to crystallize out. 

Sodium and Ammonium Alums. These alums may be 
obtained by using sodium or ammonium sulphate in place of 
potassium sulphate. These products all have nearly the same 
chemical and physical properties, being colorless, soluble salts 
which crystallize in octahedra. 

AMMONIA. When animal matter undergoes decomposition 
more or less ammonia is produced. It is also formed when 
nitrogenous organic substances are subjected to destructive dis- 
tillation. By means of the latter process, during the distillation 
of coal for the production of illuminating gas and coke, most of 
the ammonia of commerce is produced. To a limited extent 
ammonia is also obtained from the distillation of bones and other 



ELEMENTS AND INORGANIC COMPOUNDS 109 

animal matter, from putrid urine, sugar residues, and from waste 
furnace gas. 

The nitrogen in the ammoniacal liquor of the gas works is 
present in the form of free ammonia, ammonia combined as 
carbonate, sulphide, sulphydrate, sulphite, sulphocyanide and 
ferro-cyanide. As the liquor comes from the hydraulic main, 
the scrubbers and condensers, it is mixed with a large amount 
of tarry matter, which, on standing, settles out, leaving a 
fairly clear liquid which may be treated for its ammonia 
content. There are various methods employed for recovering 
the ammonia, but the one in common use is that in which the 
Feldman apparatus is employed: The settled gas liquor passes 
by means of a series of narrow tubes through a cylindrical chamber, 
where it becomes somewhat heated from the waste gases passing 
through this chamber, which is known as the " economizer." 
The heated liquor is then forced to the top of a tall tower, where 
it meets a current of steam which causes volatile ammonia com-, 
pounds to be liberated. The non-volatile compounds flow down 
the tower and coming into contact with boiling lime water free 
ammonia is produced. The free and volatile ammonia com- 
pounds are next caused to pass through a large pipe into the 
absorption vessel containing sulphuric acid. Here the sulphides 
and other volatile salts of ammonia are decomposed with the 
formation of ammonium sulphate and the liberation of hydrogen 
sulphide and carbon dioxide. These hot gases so formed are 
collected in the dome over the absorption vessel and from there 
pass into the shell of the economizer, producing the heat referred 
to above. The waste sludge from the lime treatment is drawn 
off from time to time and the liquor in the absorption vessel con- 
centrated as it becomes saturated, being sold as crude ammonium 
sulphate. 

On recrystallizing the crude ammonium sulphate and redis- 
tilling with lime, a pure gas is obtained which, being absorbed in 
water, forms the " aqua ammonia " of commerce, or the ammo- 
nium hydroxide of the laboratory. By subjecting ammonia gas 
to high pressure it is possible to convert it into a liquid. Liquid 
ammonia has extensive application at present, being used for 
producing cold in ice machines. 

Ammonium Carbonate. The commercial product is pre- 
paid by heating a mixture of the sulphate of ammonia and 
powdered calcium carbonate in iron retorts and collecting the 
sublimate formed in lead-lined chambers. The product thus 



110 ELEMENTS OF INDUSTRIAL CHEMISTRY 

obtained is a mixture of ammonium bicarbonate and ammonium 
carbamate. 

AMMONIUM CHLORIDE. This compound is manufactured 
either by absorbing the gas in dilute hydrochloric acid, or by 
neutralizing the gas liquor directly with the acid. In either case 
the resulting solution is evaporated to obtain the crystals, which 
is then purified by recrystallization or sublimation. Ammonium 
chloride is usually purified, however, by sublimation, in which 
case it is heated in iron or earthenware pots provided with a dome- 
shaped cover. The purified product collects in the dome as a thick 
crystalline cake which is removed and placed on the market as 
sal-ammoniac. Formerly this salt was made by burning dried 
camel's clung, but at present it is all prepared from gas liquor. 

Ammonium chloride is used in soldering, in the manufacture 
of dyestuffs, and in calico printing. It also has extensive appli- 
cation in electrical appliances. 

AMMONIUM NITRATE. This salt is prepared in a manner 
similar to that employed in making the chloride, except that it 
cannot be purified by sublimation. Its chief uses are in the 
manufacture of explosives and for making nitrous oxide, so-called 
laughing gas. 

AMMONIUM SULPHATE. The crude salt is dark brown in 
color and is prepared as described under ammonia. Its chief 
use is as a base for making other ammonia salts, and in the impure 
form for the manufacture of fertilizer. When purified it gives 
a white crystalline product used for fire-proofing fabrics as well 
as for other purposes. 

ANTIMONY. This element occurs in nature as the sulphide 
Sb2S3, known as stibnite. The antimony sulphide is first sepa- 
rated from the gangue by heating in a furnace with sloping floor 
along which the fused sulphide flows in a channel. This sulphide 
is then placed in a reverberatory furnace, when it is converted 
into the oxide. The oxide is heated in a crucible, when on cooling 
the metal settles to the- bottom. The metal has become very 
important owing to its application in many metallic alloys, such 
as hard lead and type metal. 

Antimony Fluoride. The compound SbF 3 is prepared 
by dissolving antimony oxide in hydrofluoric acid. This salt 
readily forms double compounds with alkaline sulphates and 
chlorides. (NH^SCU, SbFs is an example of these double salts 
and is one of the important mordants. The double fluoride 
of ammonium and antimony, 8SbF3, 2NEUF, is a useful salt, 



ELEMENTS AND INORGANIC COMPOUNDS 111 

These compounds are used as mordants, and have, to a great 
extent, replaced tartar emetic. 

ARGON. This element occurs in the air to the extent of 
0.935 per cent. It can be prepared by passing atmospheric 
nitrogen, free from oxygen and moisture, over red-hot magnesium 
ribbon: magnesium nitride is thus formed, while the argon does 
not combine. 

ARSENIC. This metal occurs in nature usually in the form 
of sulphide, such as realgar, orpiment, smalt, and arsenical pyrites. 
It is obtained from the pyrites by heating it away from the air, 
when the arsenic sublimes, leaving the iron sulphide behind. 

ARSENIOUS OXIDE. White arsenic, As 2 3j is obtained by 
roasting arsenical minerals, such as mispickel, FeAsS, cobalt ite, 
CoAsSj smaltite, CoAso, and other minerals containing arsenic. 
By far, however, the greater amount of arsenious oxide is obtained 
as a by-product in the smelting of ores containing this element 
in small quantities. The roasting is carried on in reverberatory 
furnaces with free access of air and the sublimed arsenic trioxide 
condensed in suitable chambers. It is purified by resublimation 
and collected as a white powder. By resublimation under pres- 
sure it is obtained in a vitreous variety known as arsenic glass. 
It is usually ground to a fine powder, which is slightly soluble in 
water. It is principally used as an antiseptic for preserving- 
hides: it also finds application in glass manufacture, and its 
glycerine solution is used in calico printing. 

ARSENIC ACID. By oxidizing arsenic trioxide with nitric 
acid the compound HsAsO^ is obtained as a thick syrupy 
liquid. 

SODIUM ARSENATE. By fusing together a mixture of arsenic 
trioxide and sodium nitrate the compound Na2HAs04 is obtained. 

BARIUM. This element occurs in nature in the form of 
heavy spar or barytes and as witherite. It is prepared by heating 
the oxide with magnesium. It has a metallic appearance with 
a yellowish tint. As a metal it has no practical application. 

BARIUM OXIDE. This compound can be prepared by heat- 
ing the nitrate or hydroxide to a dull red beat: It is manufac- 
tured commercially, however, by heating a mixture of barium 
sulphate and carbon in the electric furnace. 

BARIUM PEROXIDE. This is prepared from the oxide by 
heating to 500° C. in the presence of air. At a higher tempera- 
ture oxygen is again eliminated. It is used in the manufacture 
of oxygen and hydrogen peroxide. 



112 ELEMENTS OF INDUSTRIAL CHEMISTRY 

BARIUM HYDROXIDE. This compound is formed when the 
oxide is treated with water, in which it is soluble, forming a 
strongly alkaline solution. It is used for the extraction of 
sugar from molasses and to some extent in the softening of 
water. 

BARIUM CARBONATE. Barium carbonate occurs in nature 
as the mineral witherite. It is used as a raw material in making 
other barium compounds. 

< BARIUM CHLORIDE. By treating witherite with hydrochloric 
acid the compound BaCl22H20 is produced. Commercially 
barium chloride is obtained from barytes. The mineral is heated 
in a closed furnace in the presence of carbon and the resulting 
barium sulphide treated with a solution of sodium carbonate. 
The products of the reaction are barium carbonate and sodium 
sulphide, from which the chloride may be easily prepared. In 
some cases the barium sulphide is directly converted to the 
chloride by means of hydrochloric acid. It is used for the pre- 
vention of boiler scale, for the manufacture of blanc-fix and in 
the preparation of certain color lakes. 

BARIUM NITRATE. Witherite when dissolved in dilute 
nitric acid gives this compound. On a large scale it is prepared 
by double decomposition of barium chloride and sodium nitrate. 
It is used commercially to some extent for making peroxide and 
in the manufacture of fireworks to obtain a green flame. 

BARIUM SULPHATE. This compound is found in nature as 
barytes or heavy spar. The mineral is ground to a fine powder 
and used in the manufacture of paints. When produced arti- 
ficially, however, it gives a pigment of finer texture known as 
blanc-fix. The natural sulphate when heated with carbon is 
reduced to a sulphide which on dissolving in water and adding 
to a solution of zinc sulphate produces the product known as 
lithophone. 

BISMUTH. This element occurs in the native state also as 
the oxide and sulphide. , The ores are smelted in the presence of 
iron, which acts as a desulphurizing agent. The pure metal has 
a lustrous appearance like antimony, but may be distinguished 
from it by a reddish reflex. Bismuth forms easily fusible alloys 
used in making valves, wires, etc., for safety devices on boiler 
valves, fire doors and fusible plugs. 

BISMUTH NITRATE. This is obtained as a crystalline com- 
pound containing five molecules of water, when the metal is dis- 
solved in nitric acid and evaporated. It is easily soluble in & 



ELEMENTS AND INORGANIC COMPOUNDS 113 

small quantity of water, but when a large amount of water is used 
the subnitrate is produced. 

BORON. This element occurs in nature in boric acid and 
borax. It is obtained by reduction as a brown amorphous 
powder. 

BORIC ACID. This compound, also known as boracic acid, 
is found in the steam which issues from fissures in the earth in 
the vicinity of volcanoes. The steam is condensed in reservoirs 
of water built around the points from which it issues. When the 
water has become fairly well saturated it is allowed J;o settle and 
then transferred to lead-lined tanks, where it is concentrated 
to a specific gravity of 1.08. The boric acid which crystallizes is 
usually purified by recrystallization. Some boric acid is obtained 
by decomposition of borax with hydrochloric acid. It is a color- 
less crystalline solid, slightly soluble in cold water, but readily 
soluble in hot water. It is used as a flux, in fusible glazes, in 
special optical glass, and as an antiseptic and preservative. 

BORAX. Sodiimi tetraborate may be prepared by neutral- 
izing boric acid with sodium carbonate. The chief source of 
borax, however, is from the natural deposits of Thibet, and from 
the crude borax of California. Crude borax is purified by slow 
recrystallization. Commercially borax is prepared on quite a 
large scale by boiling Colemanite (Ca2BeOn -5H20) with sodium 
carbonate and sodium bicarbonate. The most common form is 
the prismatic Na^B^tOz, IOH2O, which effloresces in the air and 
melts in its water of crystallization, becoming anhydrous at a red 
heat. Borax is used as a flux, in glass and enamel making, in the 
manufacture of soap and as a preservative. 

BROMINE. Bromine is manufactured from the bromides of 
the alkali and alkali-earth metals. These salts do not occur in 
nature in quantity in high concentration and are always associ- 
ated with large quantities of chlorides. The bromides accumulate 
in the mother liquors from which the chlorides have been extracted. 
Such mother liquors serve as the chief raw material of the bro- 
mine industry. 

The principal sources are the mother liquors of various salt 
wells in the United States (Michigan and Natrona, Pa.), and 
mother liquors from the manufacture of Carnallite at Stassfurt, 
Germany. The Carnallite mother liquors contain about ^% 
bromine in the form of magnesium bromide. The concentration 
of the American mother liquors is higher and has enabled the 
American producers to wrest a considerable share of the world's 



114 ELEMENTS OF INDUSTRIAL CHEMISTRY 

market from their foreign competitors who at one time enjoyed 
a practical monopoly. 

From such mother liquors bromine is liberated either by 
the action of chlorine or by direct electrolysis. The former 
method (Process of Dow, etc.) is simpler and probably cheaper 
and better. It depends upon the simple reaction 

MgBr 2 + Cl 2 - MgCl 2 +Br 2 . 

The mother liquor containing bromide is caused to meet a 
stream of chlorine on the counter current principle in a stoneware 
tower, which may be of the Lunge plate tower type or filled with 
stoneware balls to increase the surface of contact. The amount 
of chlorine is regulated so that practically all is used up in the 
liberation of bromine so that the secondary formation of bromine 
chloride is minimized. A large part of the liberated bromine 
remains dissolved in the liquor flowing from the reaction tower. 
It is collected in granite wells and heated to boiling with live 
steam which expels the bromine. This is condensed in stoneware 
worms. The crude bromine contains about 2 to 4 per cent 
chlorine. The chlorine may be removed by treating with ferrous 
bromide solution and redistilling, the chlorine being held back 
as ferrous chloride. The crude bromine may also be purified 
by being heated very slowly to a point just below the boiling 
point of bromine and held at this temperature (59° C.) for thirty- 
six to forty hoars. 

The electrolytic processes depend upon the fact that bromides 
decompose at a lower voltage than chlorides and hence are first 
decomposed. Diaphragm cells are used. Owing to the low con- 
centration and the large bulk of liquid to be handled the effi- 
ciency is low. 

In the processes depending on displacements by chlorine, the 
chlorine may be generated within the liquor by the action of 
muriatic acid on manganese dioxide, but the use of externally 
generated chlorine is simpler and gives a better control of the 
process. 

Bromine is used in metallurgy (bromo-cyanogen process), in 
the manufacture of bromides for use in pharmacy and the photo- 
graphic industries, and also as a disinfectant. 

CADMIUM. This element usually accompanies zinc in its 
ores. It is easily separated, as it distills off before the zinc. It 
<Joes not alter easily when exposed to the air, but becomes covered 



ELEMENTS AND INORGANIC COMPOUNDS 115 

with a brown oxide when heated. It is used in various metallic 
alloys to reduce the melting point. With mercury it forms a 
soft amalgam which hardens very easily, and for this reason is 
used as a cement for filling teeth. 

CADMIUM SULPHIDE. By passing hydrogen sulphide into 
a solution of a cadmium salt a bright orange yellow precipitate 
is produced. This may also be formed by the addition of sodium 
sulphide. It is known commercially as cadmium yellow and is 
used for tinting paints. 

CAESIUM. This is one of the rare elements and is of no 
commercial value. 

CALCIUM. This element is very abundant and widely dis- 
tributed in nature. In the form of carbonate it occurs as marble, 
chalk, and limestone; as a phosphate it occurs as apatite; as a 
sulphate it occurs as gypsum; as a fluoride it occurs as fluorspar; 
as a silicate it occurs as wollastonitc. It may be obtained in the 
elementary condition by the electrolysis of fused calcium chloride. 
It has a silvery luster which is of a yellowish tint. It is employed 
commercially for removing the last traces of carbon from metals 
or alloys. It is also used as a reducing agent in some organic 
preparations. 

CALCIUM CARBIDE. When lime and carbon are mixed to- 
gether in proper proportions and the mixture heated to an 
extremely high temperature the lime is reduced and the metallic 
calcium unites with the excess of carbon present to form the car- 
bide. CaCo. In general the electric arc is used as the source of 
heat, though resistance systems have been more or less success- 
fully employed. The reaction which takes place in the furnace is 

CaO+3C = CaC 2 +CO. 

This reaction would require a mixture of 875 parts by weight of 
lime to 563 parts of carbon, though in actual practice the pro- 
portion of carbon used for the above quantity of lime rises as high 
as 650 parts, the excess being consumed in other ways than by 
the above reaction. 

The original carbide furnace consisted merely of a basin into 
which dipped two electrodes, between which an arc was sprung, 
the reacting mixture being fed directly into the arc. The melting- 
point of the carbide is in the neighborhood of 1800° C, and so 
the mass sets almost as fast as formed. When the basin was full 
of set carbide the whole was removed from under the electrodes, 



116 



ELEMENTS OF INDUSTRIAL CHEMISTRY 




Fig. 56. 



allowed to cool and the carbide dug out. The operation was thus 
an intermittent one, and rather low energy efficiency was attained. 
A continuous furnace has recently been put into operation with 
much better results. 

Fig. 56 shows one form of this furnace. It consists of a ring 
mounted on trunnions, so as to revolve in a vertical plane. The 
whole is made of cast-iron segments bolted together, each piece 
having its own individual lining of carbon. Hanging down be- 
tween the two sides is a carbon electrode C forming one terminal 
of the circuit, the other terminal being the carbon lining of the 

furnace. The mixture of car- 
bon and lime is fed into an 
arc sprung between the elec- 
trode and the furnace walls. 
As the carbide is formed the 
furnace is revolved away from 
the electrode, making space 
for more product, cover plates 
A being put on as necessary. 
As the furnace revolves the 
material inside cools, and by 
the time it reaches the side 
opposite the electrode is so cold that the side and cover plates 
on this side may be removed and the carbide taken out, the side 
plates again being reassembled at the top. In this way the fur- 
nace can be run continuously. Another form of this furnace 
uses instead of the carbon lining of the furnace for one of the poles 
another electrode directed towards the first one, between which 
the arc is sprung and the material fed. The furnace in use at 
Niagara Falls is of this latter type. It is 8 ft. in diameter, the 
outer ring being about 24 ins. deep. It revolves once in 24 
hours. With an energy consumption of 500 horse-power, one 
furnace will produce 2 tons of carbide per day. Only about 40 
per cent of the heat equivalent of this energy is absorbed in the 
reactions. 

Very recently this revolving type of carbide furnace is being 
replaced by a multiphase furnace of considerably larger energy 
consumption. One such furnace in this country of approximately 
10,000 horse-power, using six electrodes connected up in two three- 
phase circuits, is turning out almost 11 pounds of 85 per cent 
carbide per horse-power day from a furnace charge consisting 
of very pure lime crushed to egg size and chestnut coke con- 



ELEMENTS AND INORGANIC COMPOUNDS 117 

taining 90 per cent fixed carbon, the charge being proportioned 
60 per cent lime and 40 per cent coke. 

CARBORUNDUM. When silica is heated to a very high 
temperature in contact with an excess of carbon a carbide, SiC, 
is formed. This is the well-known abrasive called carborundum. 
The reactions by which it is made may be represented as 

Si0 2 +3C = SiC+2CO. 

The arc furnace used in the production of calcium carbide cannot 
be employed in the manufacture of carborundum, because of the 
liability of overheating. Although a high temperature is needed 
for its formation, if that temperature is exceeded metallic silicon 
will be volatilized from the formed carborundum and graphite 
will be left behind. It was this accidental discovery that led to 
the development of the artificial graphite industry to be described 
later. In practice the carborundum furnace consists of a bed 



Fig. 57. 

of firebrick 16 ft. long by 5 ft. wide serving as a permanent 
foundation. The rest of the furnace structure, as the end and 
side walls, are laid dry and torn down, and replaced with each 
run of the furnace. The mixture with which the furnace is 
charged, 3.5 tons of carbon, 6 tons of sand and 1.5 tons of salt 
is next shoveled on this foundation, carrying up with it the side 
walls as necessary for its retention. Through the center of this 
mixture M, in Fig. 57, is placed a core of granulated carbon which 
serves as the resistor, for the development of the electrical heat 
in the furnace. The ends of this core are in contact with the 
permanent end connections E, consisting of carbon bars, between 
which the copper conductors are laid. Such a furnace takes about 
1000 horse-power and runs for 36 hours, at the end of which time 
3 to 4 tons of commercial carborundum have been made. After 
such a run the granulated coke forming the heating core has been 
graphitized, and immediately surrounding and in contact with it 
is a layer of graphite produced from overheating the carborundum 



118 ELEMENTS OF INDUSTRIAL CHEMISTRY 

first formed there. Surrounding this graphite is the crystallized 
corborundum in a layer a foot or more thick, beyond which is 
found the reduced and uncrystallized carbide, the partially reduced 
mixture and finally unaltered mixture. The last three products 
are usually charged back into the next furnace run, though an 
attempt has been made to utilize the partially reduced material 
as a refractory. 

ARTIFICIAL GRAPHITE. The overheating of a carborundum 
furnace led to the discovery that by suitable decomposition of a 
carbide graphite is left behind. Heating of pure carbon will 
not transform it into graphite, it having first to pass through the 
state of a carbide, which requires that some metal or metallic 
oxide be mixed with it. In practice, anthracite carrying 8 to 
10 per cent ash, uniformly distributed through it, is used for the 
furnace charge. It may be either molded into shape first and 
then graphitized, or else graphitized in powdered form and then 
used for all purposes of ordinary graphite. It is practically pure, 
running over 99.5 per cent graphite, all the other impurities 
having been volatilized at the temperature of the furnace. Fig. 

58 shows the furnace used for 
graphitizing small carbon elec- 
trodes. These small electrodes are 
packed transversely into the fur- 
nace, which bears some resem- 
Fig. 58. blance to the carborundum furnace. 

Between the piles of electrodes 
thin layers of granular carbon are inserted and the whole furnace 
covered over with carborundum residue. The current is led in 
through the massive electrodes at the end and traverses both 
the pile of electrodes and the granular packing. The major 
portion of the heat is generated in the granular portion of the 
circuit. Such a furnace is 15 ft. long and consumes 1000 horse- 
power, the run being about 20 hours. Both the carborundum 
furnace and the graphite furnace are the invention of Mr. E. G. 
Acheson, of Niagara Falls, N. Y. 

CALCIUM CARBONATE. Calcium carbonate occurs in many 
minerals and is a constituent of many animal and vegetable sub- 
stances. It is decomposed by heat and by mineral or organic 
acids. In the precipitated form it is used in pharmaceutical 
preparations while the natural form is employed in paints, in 
scouring mixtures, and for a variety of other purposes. 

CALCIUM OXIDE. By heating calcium carbonate the carbon 




ELEMENTS AND INORGANIC COMPOUNDS 119 

dioxide is eliminated and the oxide results. Its method of 
preparation and its applications are given in Chapter VII. 

CALCIUM HYDROXIDE. This compound is produced when 
water is added to calcium oxide. It is only slightly soluble in 
water (1.3 parts per thousand). This dilute solution has an 
alkaline reaction and is known as lime water. When an excess of 
calcium hydroxide is present it is called milk of lime. The milk 
of lime has many commercial applications, which will be considered 
at other places in the text. 

CALCIUM CHLORIDE. This compound is obtained as a 
by-product from several industrial operations, especially from the 
manufacture of soda by the ammonia process. It may also be 
prepared by acting upon calcium carbonate with hydrochloric 
acid. It is very soluble in water. The fused product is employed 
for drying gases. The crystalline product is used in refrigeration, 
for dust prevention, for anti-freezing solutions and for other 
purposes. 

CALCIUM FLUORIDE. This compound is found in nature in 
the mineral fluorspar. It is used as a source of hydrofluoric acid 
and a flux in metallurgical operations. 

CALCIUM NITRATE. By dissolving calcium carbonate in 
nitric acid this compound is produced. It is also obtained in the 
fixation of nitrogen mixed with calcium nitrite. The crude 
material thus formed is employed in the manufacture of fertilizers. 

CALCIUM SULPHIDE. This compound is obtained by heating 
calcium sulphate with charcoal. It is used in the manufacture 
of luminous paints. 

CALCIUM SULPHATE. This compound occurs in nature as 
gypsum, containing two molecules of water of crystallization. 
When this is heated gently part of the water is driven off, the 
product known as plaster of Paris being produced. See Chapter 
VII. 

CARBON. This element is widely distributed in nature in 
the free condition; it is also found in inorganic and in organic 
substances. In combination with the metals it occurs as marble, 
chalk and other carbonates; with hydrogen it occurs in petrol- 
eum and paraffin; with hydrogen and oxygen in all vegetable 
and animal matter; and with oxygen as carbon dioxide and 
carbon monoxide. In the free state it is found as the dia- 
mond, graphite and in the amorphous condition. 

This element forms thousands of compounds which are of 
great commercial value as well as of scientific interest. The 



120 ELEMENTS OF INDUSTRIAL CHEMISTRY 

study of these compounds constitutes a branch of chemistry in 
themselves called Organic Chemistry. Many of these compounds 
will be considered in other sections of the text, while two, 
which are more or less of an inorganic nature, will be taken up at 
this point. 

CARBON DISULPHIDE. This compound is prepared by pass- 
ing the vapor of sulphur over highly heated charcoal. Vertical 
iron or clay retorts are usually employed, and the sulphur intro- 
duced through a tube on the side. The uncombined sulphur is 
collected in a special receiver, while the carbon disulphide passes 
on and is condensed. The product thus obtained is very impure, 
and must be purified by treating with lead acetate, then with 
lime water and finally by redistilling. Practically all the carbon 
bisulphide, however, used in the United States to-day is made 
in the electric furnace. This furnace consists of a tall shaft 
divided by an inside wall into two annular spaces, united below 
in a common hearth. The inside shaft is kept filled with char- 
coal and the outside ring with sulphur. Electrodes pass through 
the hearth walls into the charcoal chamber. The electric heat 
generated in the furnace warms up the sulphur and charcoal, 
the sulphur vapors rising up through the hot charcoal and react- 
ing when a zone of suitable temperature is reached. The carbon 
bisulphide vapors are taken from the top of the furnace through 
iron pipes and led to suitable condensers. These furnaces are 
practically automatic in operation; when they get too hot sul- 
phur melts in the outer ring and runs down into the crucible, 
covering up part of the electrodes, thus increasing the resistance 
and so lessening the energy consumed in the furnace. The 
reverse phenomena take place as the furnace cools down below 
normal. When pure, carbon disulphide is a nearly colorless 
mobile liquid, with only a slight odor. The commercial article, 
however, has a very disagreeable odor, due to the presence of 
sulphur compounds. It is heavier than water, boils at 46.5° C, 
and its vapor inflames at 149.5° C. It is a good solvent for sul- 
phur, phosphorus, resins, waxes and fats. It is also used, to 
some extent, as a germicide and insecticide. 

Carbon Tetrachloride. This compound is made by 
passing the vapor of carbon disulphide and dry chlorine through 
a heated earthenware tube; or it may be prepared by passing 
chlorine over liquid carbon disulphide in which a little iodine has 
been dissolved. Recently electrolytic processes have -come into 
use by which a pure product is more economically produced. 



ELEMENTS AND INORGANIC COMPOUNDS 



121 



Sulphur monochloride is formed at the same time and is removed 
from the carbon tetrachloride with milk of lime and potash, and 
then distilled . Carbon tetrachloride is a non-inflammable heavy 
liquid, having a specific gravity of 1.637 and a boiling-point of 
76.5 c C. It is a good solvent for gums and resins and is also 
largely used in cleaning solutions. 

CERIUM. This element is found in the mineral cerite and 
forms both cerous and eerie salts. 

CHLORINE. The primary raw materials for the manufacture 
of chlorine are the alkali chlorides, common salt (sodium chloride) 
and potassium chloride. A secondary raw material is hydro- 
chloric acid, produced by the action of sulphuric acid upon com- 



sees 





Fig. 59. 



mon salt. It was formerly almost a waste product of the Leblanc 
process for manufacturing sodium carbonate, and is still available 
in England in enormous quantities at a very low price. 

The manufacture of sodium hydroxide and chlorine directly 
from common salt has been accomplished only electrolytically. 
Of these electrolytic processes four only will be described. A 
more exhaustive treatment of the subject will be found in the 
Manual of Industrial Chemistry, Chapter VIII. Following the 
electrolytic methods will be given two of the chemical processes 
employed. 

Acker Process. In the Acker process, Fig. 59, solid salt is 
fused by passing through it a current of very high density. Chlo- 
rine is liberated at the anodes of Acheson graphite and is drawn 



122 ELEMENTS OF INDUSTRIAL CHEMISTRY 

off by a slight suction into brick conduits. Sodium is liberated 
at the cathode, a shallow body of molten lead, with which it 
immediately alloys. This alloy is fluid as long as the percent- 
age of sodium is very low. The body of molten lead is kept in 
continuous motion in one direction and passes through a short 
connecting channel under the hearth to a second compartment 
called the well. It is here elevated by means of a sort of 
steam injector, which consists of a vertical cast-iron pipe dip- 
ping into the well and pointed upward. The well has a curved 
cast-iron cover. On admitting steam, the lead sodium alloy is 
projected upward against the face of the cover and decomposed 
into metallic lead, caustic soda and hydrogen. The products 
are deflected downward into a third small compartment, the 
caustic chamber. Here the lead sinks by gravity and flows 
back into the cell to take up more sodium and go the round 
anew. The caustic soda, being lighter, collects in an anhydrous 
condition at the top of the caustic chamber and overflows from 
a spout into a collecting vessel. Any excess of steam with the 
hydrogen, which burns quietly, escapes at the same point. The 
action is entirely continuous. The rate of flow of the cathode 
lead is controlled by the rate of steam supply, which is usually 
a little greater than that theoretically necessary to convert the 
metallic sodium into hydrate. The bath of electrolyte is kept 
up to volume by periodically shoveling in solid salt. The cell 
or furnace is made of cast iron, that portion which contains the 
salt being lined with two rows of magnesia or ordinary firebricks 
laid in without bond. The molten salt penetrates between the 
cracks and freezes in the outer layer, making the lining impervious. 
Each cell is about 3X6 ft., and carries four anodes having an 
effective surface of about 3 sq. ft. in all. The under surface 
of the anodes are grooved to prevent the chlorine accumulating 
upon them, which would raise the resistance. The current 
very high, 8300-8500 amperes, a current density of 2800 amperes 
per square foot at the anodes. The voltage is about 6.5 volts 
under normal operating conditions. The output of each cell is 
about 550 lbs. anhydrous sodium hydroxide and 495 lbs. chlorine 
per 24 hours. The caustic is very pure. It contains 1 per cent 
total impurities (a little salt which gets in mechanically and a 
little carbonic acid taken up from the air) . It is collected in large 
pots holding from 10 to 13 tons, where it is kept molten to allow 
impurities to settle out and is treated with a little sodium hypo- 
sulphite to destroy traces of sodium manganate, etc., which gives 



ELEMENTS AND INORGANIC COMPOUNDS 



123 



it a green color as it runs from the cells. While still liquid it 
is bailed into the cast-iron drums in which it is sold. 

The good features of the process are the high output per cell, 
many times larger than that possible with any wet process cell 
of similar size, the saving of the expense of boiling down weak 
caustic liquor and of dissolving salt, etc. The drawbacks are 
the somewhat high voltage necessary and the dilution of the 
chlorine which is drawn off, mixed with about 20 or 30 times 
its volume of air. This weak chlorine is well adapted for certain 
purposes, but not all. Its use in manufacturing bleaching powder 
necessitates the use of mechanical absorbers. 

Castner-Kellner Process. This may be considered as the 
type of mercury cathode processes, of which it is the oldest and 
most generally successful example. 

The Castner cell, Fig. 60, consists of a slate box 4 ft. long, 




Fig. 60 



6 ins. deep and 4 ft. wide, divided into three compartments by 
partitions extending to within ^ of an inch of the bottom. 
These compartments are kept separate by a layer of mercury 
covering the entire bottom of the apparatus. The outer com- 
partments are filled with strong salt solution and the center com- 
partment with pure water. In each outer compartment there 
are several T-shaped anodes of Acheson graphite, having the 
lower surface within one inch of the mercury. In the center 
compartment is an iron grid which serves as the cathode. The 
cell is pivoted on one end and rests on an eccentric on the other, 
which raises and lowers \ in. once a minute, imparting a rock- 
ing motion and causing the mercury to flow backward and for- 
ward between the compartments. On passing the current the 
salt in the outer compartments is decomposed, liberating chlorine 
at the anodes, which is drawn off by slight suction. Sodium 



124 ELEMENTS OF INDUSTRIAL CHEMISTRY 

is liberated at the intermediate cathode of mercury and alloys 
with it. The sodium mercury alloy flows into the center compart- 
ment, where it plates out sodium at the iron cathode. The 
sodium instantly combines with the water, forming caustic soda 
and hydrogen. The caustic soda dissolves while the hydrogen 
is allowed to escape into the room. Part of the current must be 
shunted off before passing to the final iron cathode. Only 90 
per cent of the charging current is allowed to pass through the 
discharging cell, otherwise mercury would pass into solution 
in the cathode compartment, forming HgO, destroying the 
continuity and clean metallic liquid character of the mercury and 
causing a heavy loss of this expensive material. 

The salt solution flows through the anode compartment 
continuously, being brought back to its original high concentra- 
tion by the addition of salt outside the cell and then returned 
for reuse. As the sulphates in the brine accumulate, they are 
from time to time removed by precipitation with barium chloride. 
The water in the center compartment is left until the caustic 
soda has raised its gravity to 1.3. The caustic soda solution is 
then run off and replaced by fresh water. The lye is boiled 
down in cast-iron pots till anhydrous, and is packed molten into 
iron drums. It is very pure, often 99 per cent actual sodium 
hydroxide. 

The cells are inexpensive to construct and last indefinitely, 
likewise the iron cathodes. The anodes last a year or more. 
The current at the anode is about 630 amperes per cell, of which 
10 per cent is shunted off before discharging in the cathode com- 
partment. The voltage is about 4.3. The current efficiency is 
nearly 90 per cent, energy efficiency 47 per cent. The current 
density at the anode is about 150 amperes per square foot, and 
at the mercury 110 amperes per square foot. The current which 
can be used is limited by the necessity of keeping the temperature 
of the cell below 40° C, at which point chlorate begins to form. 
Each cell decomposes per 24 hours, 65 lbs. sodium chloride, 
forming 44 lbs. sodium hydroxide and liberating 39.4 lbs. chlorine. 
The output per horse-power per 24 hours is 12.0 lbs. sodium 
hydroxide and 10.8 lbs. chlorine. 

The two factors which have most largely contributed to the 
success of this type of cell are : 

(1) The rocking mercury cathode. 

(2) The cathode shunt. 

Each Castner cell requires about 150 lbs. of mercury, which 



ELEMENTS AND INORGANIC COMPOUNDS 



125 



it is essential to keep bright and clean, and of which there must 
be no loss. The mercury is not dissolved by the brine as long 
as it is electrically negative and does not oxidize in the center 
compartment unless denuded of sodium; hence the necessity 
of a higher charging than discharging current. 

Diaphragm Processes. In cells of this type the anode and 
cathode are separated by a porous partition, which in most 
successful cells is in close contact with the cathode. Concen- 
trated salt solution is usually fed into the anode compartment 
and flows toward the cathode under slight head. The dia- 
phragm controls and regulates the forward motion of the salt 
solution and retards the backward flow of the caustic soda formed 
at the cathode. The caustic liquor formed at the cathode is 
drawn off continually. If the rate of flow is high the crude 
cathode liquor contains much salt, and the percentage of sodium 
hydroxide is low; if the flow is slower the concentration in sodium 
hydroxide will be higher and the lye will contain less salt, but 
there will be greater diffusion of sodium hydroxide backward 
through the anode compart- 
ment, with recombination, 
etc., and loss in electrical 
efficiency. 

Townsend Cell. In the 
Townsend cell, which is 
shown in cross-section in 
Fig. 61, the anodes are of 
graphite, the cathodes are 
perforated iron plates, sep- 
arated from the anode com- 
partment by vertical dia- 
phragms which adhere closely 
to the iron cathodes. The 
outer surfaces of the cathode 
plates are bathed in kerosene 
in the cathode compart- 
ments. The anode compart- 
ment is kept filled with brine. 
A hydrostatic pressure is 

maintained whereby a portion of the brine flows slowly from the 
anode into t he cathode compartments. As soon as current is pass- 
ing, i bis escaping brine is charged with the caustic soda formed by 
electrolysis. Passing through the perforated iron plates it meets 




UEOUTLLT 



Fig. 61. 



126 ELEMENTS OF INDUSTRIAL CHEMISTRY 

the kerosene bath and forms oily drops which detach from the 
walls and sink to the bottom of the kerosene, out of electrical 
or chemical contact with the system, and is continuously removed. 
The spent anode brine is pumped continuously from the anode 
compartment to a tank, where it is saturated with salt and the 
chlorine trapped off. It is then returned to the cell. The cells 
are made in rather large units and carry from 4000 to 6000 
amperes per cell. The composition of the cathode liquor 
varies with the rate of percolation. With the rate found most 
advantageous in practice the composition is about 150 grams 
sodium hydroxide and 213 grams sodium chloride per liter, with 
lower hydrostatic pressure and reduced percolation— the com- 
position can be brought to sodium hydroxide 250 grams, sodium 
chloride 140 grams. This cell can be run at very low voltage, as 
low as 3.5, with a current density of 70 amperes per square foot 
at the anode, but with increased current density (140 amperes 
per square foot at the anode), the voltage rises to about 4.7. 
While the yield of sodium hydroxide and chlorine per horse-power 
is less at the high density the output per cell is greater, and it has 
been found on the whole more economical to sacrifice power to 
greater output per unit of plant. 

Chemical Processes. Of the purely chemical processes for 
preparing chlorine two survive, the Weldon and the Deacon 
processes. Both use muriatic acid as the source of chlorine. 
Because of the expense incident to transporting this acid, where- 
ever chlorine is produced in a large way chemically, the acid is 
made on the spot. 

Weldon Process. Muriatic acid is oxidized by manganese 
dioxide, liberating chlorine at a moderate temperature. . 

Mn0 2 +4HCl = MnCl 2 +2H 2 0+Cl2. 

The primary source of the dioxide is the mineral pyrolusite, 
which contains from 50 to 70 per cent of manganese dioxide. 
High manganese dioxicle content is very desirable for chlorine 
manufacture, and less than 57 per cent renders the mineral unsuit- 
able for the purpose. The muriatic acid should be of high 
concentration, 30 per cent upward of actual hydrochloric acid 
and fairly free from sulphuric acid, otherwise the regeneration 
of the manganese dioxide becomes difficult or impossible and 
the process unprofitable. The generation of chlorine is always 
conducted in stoneware stills (firebrick, sandstone), etc., which 



ELEMENTS AND INORGANIC COMPOUNDS 127 

may be of rather variable design. In starting with pyrolusite, 
the mineral is placed in the still first, on a raised platform, then 
the acid, preferably warm, is run in gradually, finally the still is 
moderately heated by blowing in a current of live steam. The 
muriatic acid acts on the dioxide until its concentration is reduced 
to about 5 per cent actual hydrochloric acid. With recovered 
manganese the acid is utilized down to about 2 per cent. The 
chlorine is evolved in a steady stream and is conducted by lead 
or stoneware pipes to the point of utilization. Since pyrolusite 
is fairly expensive, the profitable production of chlorine necessi- 
tates the recovery of the manganese from the spent still liquor. 
The Weldon process, which is the most successful method of 
doing this, is based on the fact that freshly precipitated man- 
ganous hydroxide suspended in a solution of calcium chloride 
is easily converted into peroxide by a current of air forced through 
the liquid, if there be present an excess of lime. The excess of 
lime is essential. 

Process of Recovery. The spent liquor from the still is run into 
a neutralizing well, where it is treated with ground chalk, or better 
with regenerated manganese mud. The free hydrochloric acid 
is thus neutralized, and any iron present is precipitated. The 
residual chlorine dissolved in the liquor is carried off along with 
the evolved carbon dioxide to a tall chimney, whence it escapes, 
or it may be removed by passing through a scrubbing tower. 

The neutralized liquor is allowed to settle. for a few hours, 
when the clear solution is run into the oxidizers. These are iron 
tanks 10 ft. in diameter and 30 ft. high, with a perforated pipe 
at the bottom through which air is admitted under pressure. 

The oxidizer is about half filled with manganese liquor (aver- 
aging 60 grains per liter manganese as manganese dioxide). 
By means of live steam the liquid is heated to 55° C. Lime 
water, prepared by slaking pure lime very low in magnesium, 
is then run in till all the manganese is precipitated as manganous 
hydroxide. Then one-fourth to one-third excess is added. 
Meanwhile the air is blowing full blast through the liquor. The 
liquor is at first yellow but gradual^ becomes black. The first 
blowing is continued three to five hours, till the liquor, which 
was at first strongly alkaline, is nearly neutralized and no more 
manganese dioxide forms. 

About one-fourth as much manganese liquor as originally 
used is then added, and blowing is continued for another two 
hours. 



128 ELEMENTS OF INDUSTRIAL CHEMISTRY 

The mud is then run into settlers, where it remains until the 
precipitate subsides. The clear supernatant solution of calcium 
chloride is then run off as a waste. 

The current of air must be very powerful, otherwise what is 
known as a stiff batch is liable to form. If there is not sufficient 
excess of lime the oxidation is only partial and what is known as 
a red batch is formed. This consists chiefly of MJI3O4. 

About 168 cu. ft. of air are required to produce 1 lb. of man- 
ganese dioxide. 

The use of recovered manganese mud greatly simplifies the 
production of chlorine. Very much larger stills, usually pentag- 
onal, are used. Muriatic acid is run into the still about 2 ft. 
deep, then gradually manganese mud is admitted until an even 
current of chlorine is produced. Finally, to utilize the last of 
the acid and drive off the dissolved chlorine, steam is blown 
in. The spent liquor then goes back to the recovery plant. 

The reactions which occur in recovery are about as follows : 

I. 100MnCl 2 + 160CaO = 100MnO+60CaO+100CaCl 2 . 
II . lOOMnO + 60CaO + 860 = 48CaO • Mn0 2 + MMnO • Mn0 2 
+ 12CaO-2Mn0 2 . 

III. 48CaOMn0 2 + 24MnCl 2 = 24CaO-2Mn0 2 + 24MnO+ 

24CaCl 2 . 

IV. 24MnO+120 = 12MnO-Mn0 2 . 

From 124MnCl 2 (original 100 and second addition of 24) 
there are produced 98 Mn0 2 (along with 36 CaO and 26MnO). 

Deacon Process. The Deacon process is based on the oxida- 
tion of gaseous hydrochloric acid by the oxygen of the air in the 
presence of a suitable catalyzer. 

2HC1+0 = H 2 0+C1 2 . 

The catalyzer most used is copper chloride, which functionates 
as follows: 

(1) 2CuCl 2 = Cu 2 Cl 2 +Cl 2 ; 

(2) Cu 2 Cl 2 +0 2 = 2CuO+Cl 2 ; 

(3) 2CuO+4HCl = 2CuCl 2 +2H 2 0. 

This reaction begins at 250° C. and reaches its maximum at 400° 
C. The rate of action of the catalyzer depends upon the surface 
exposed more than on the amount, and therefore the catalyzer 
used in practice is broken bricks or burnt clay balls which have 



ELEMENTS AND INORGANIC COMPOUNDS 129 

been soaked in copper solution (3 per cent) and dried. The 
reaction is slightly exothermic, but heat must be supplied to 
make up for the loss by radiation, etc. In practice about 60 
per cent of the hydrochloric acid is decomposed, but the rest is 
recovered as weak acid. The catalyzer soon loses its activity 
from a variety of causes, the principal of which seem to be the 
presence of sulphuric acid and arsenic in the muriatic acid. 

The gases, hydrochloric acid, air and moisture, from the 
decomposition of salt b} r sulphuric acid in an ordinary salt cake 
furnace, are cooled by passing through long glass pipes and a 
small tower filled with coke to remove moisture. They next pass 
to an iron preheater, where they are heated to 400° C. (hot, dry 
hydrochloric acid has little action on iron). The hot gaseous 
mixture then passes through the decomposer filled with the con- 
tact substance, the temperature of which is carefully regulated. 
The decomposition is here effected, the escaping gases being 
chlorine, water in the form of steam, hydrochloric acid, nitrogen, 
and a little oxygen. 

The gaseous mixture is first cooled by passing through a 
long series of pipes. The hydrochloric acid is next removed 
by washing with water in a scrubbing tower, and is finally dried 
by washing with sulphuric acid in a lead-lined tower. The con- 
tact substance is removed every two weeks, one-sixth at a time, 
thus each portion remains in service twelve weeks. 

The Deacon process produces chlorine of about 5 to 8 per cent 
volume concentration. This is its chief drawback. It produces 
chlorine more cheaply than the Weldon process, but the plant 
is expensive and there have been few new Deacon installations 
*ince the advent of the newer electrolytic processes. 

In the Weldon process about 35 per cent of the hydrochloric 
acid is converted to chlorine, the rest to waste calcium chloride. 
In the Deacon process about 60 per cent is converted and the rest 
recovered. 

Hypochlorites. Chlorine being a gas, does not admit of easy 
transportation as such. It may be liquefied by combined cooling 
and pressure, and can then be shipped under pressure in iron 
cylinders, which latter are not acted upon by dry liquid chlorine. 

Chlorine combines with aqueous solutions of the alkaline and 
alkaline earth hydrates, or with the hydrates in the presence of 
moisture-forming hypochlorites. 

2NaOH+Cl 2 = NaOCl+NaCl-f-H 2 0. 



130 ELEMENTS OF INDUSTRIAL CHEMISTRY 

The hypochlorites are very powerful bleaching and oxidizing 
agents. Calcium hypochlorite is the cheapest powerful oxidizing 
agent that we have. Their value depends in most cases upon 
the ease with which they give up oxygen to oxidizable organic 
matter, rather than to any action of the contained chlorine. 

Ca(OCl) 2 = CaCl 2 + 2 . 

» Aqueous solutions of hypochlorites are produced in large 
quantities for use at the place of manufacture. Because of 
their bulk (it is difficult to prepare hypochlorite solutions much 
over 130 grams hypochlorite per liter) and instability, such 
solutions are seldom transported. Occasionally bleach liquor 
(calcium hypochlorite solution) is shipped a few hundred miles 
in tank cars if it can be used immediately. 

Sodium and potassium hypochlorite solutions (Eau de Javelle, 
Labarraque solution) are made to some extent by the direct 
action of chlorine gas upon solutions of the respective alkali 
hydrates for use in laundry work, bleaching and disinfecting. 
They are more commonly produced from calcium hypochlorite 
by double decomposition. 

Ca(OCl) 2 +Na 2 C0 3 = 2NaOCl+CaCO,. 

Calcium hypochlorite is cheaper and equally good for many 
purposes. It is made by absorbing chlorine in milk of lime, 
which takes it up with great avidity. The manufacture is very 
simple. It is merely necessary to keep the lime in excess through- 
out and to keep the temperature below 35° C. If the chlorine 
gets in excess, or the temperature above 37° C, rapid decomposi- 
tion and formation of chlorate begins. The presence of iron 
likewise tends to cause decomposition, particularly if there be 
little excess of lime. In the manufacture of bleach liquor it is 
preferable to dilute the chlorine with air, as the danger of local 
overheating is thereby greatly reduced. The apparatus in 
which bleach liquor is made and stored is commonly constructed, 
or at least lined with Portland cement concrete, which is not 
acted upon and answers the purpose admirably. Fig. 62 shows a 
very good type of bleach liquor machine in section. A mixture 
of lime and water meets a stream of chlorine on the counter- 
current principle, is elevated by a centrifugal pump, more lime 
is added and the operation is repeated till the entire charge is 



ELEMENTS AND INORGANIC COMPOUNDS 



131 



up to the desired strength, the operation being entirely continuous 
and automatic except as regards the addition of lime. 

Although calcium hypochlorite is used in solution, it is man- 
ufactured for sale in the solid condition, which is more stable 
and more easily transported. Slaked lime Ca(OH) 2 , containing 
a slight excess of water (2 to 5 per cent) readily takes up 
chlorine, forming bleaching powder which has the composition 

CaO-CaOCl 2 +2H 2 0. 



1 EXHAUST 




CHLORINE 



Fig. 62. 



The CaO in the best bleaching powder amounts to about 10 per 
cent. Bleaching powder is readily soluble in water; the excess 
line forming a sediment : 

2CaOCl 2 +H 2 = Ca(OCl) 2 + CaCl 2 +H 2 0. 

In making bleaching powder burnt lime low in magnesia and 
carbonic acid is first slaked so as to contain about 26 per cent 
water. It is then carefully sifted through iron screens and allowed 



132 ELEMENTS OF INDUSTRIAL CHEMISTRY 

to cool completely. It is then spread in a thin layer 3 or 4 ins. 
deep on the floor of a so-called " chamber," a room usually about 
6 J ft. high. Chlorine gas is admitted through the roof and 
slowly passes to another chamber in series after the lime in the 
first chamber has taken up most of the chlorine. It usually takes 
about twenty-four hours for the lime to become completely 
saturated. In case lime deeper than 2 ins. is placed on the floor, 
it becomes necessary to interrupt the gasing and for workers to 
enter the chamber and turn the lime with a spade. Finally the 
bleach is shoveled into wooden casks or iron drums painted with 
asphalt paint. The chlorine must be fairly dry and must not 
be admitted too rapidly. The temperature of the chamber is 
kept below 45° C. Chlorine diluted with air to about 40 per 
cent by volume works well. With gas less than 30 per cent 
chlorine, mechanical absorbers or shelf absorbers with very thin 
layers of lime must be used instead of chambers. The ordinary 
bleach chambers are constructed of lead, stone or cement, with 
usually an asphalt floor. They may be quite large, 30 by 100 ft. 
is a common size, and must be provided with suitable doors, peep 
holes, etc. Two hundred square feet of chamber floor is necessary 
for each ton of bleach produced per week. 

CHROMIUM. Chromium occurs in nature in the mineral 
chromite. It is prepared on a commercial scale by the Goldschmidt 
process, which consists in fusing a mixture of powdered aluminium 
ancl chromium oxide. When added to other metals it causes them 
to become much harder and consequently has found extensive 
application in the manufacture of what is known as chrome steel. 

CHROMIUM OXIDE. This compound is produced by heating 
chromium hydroxide, ammonium dichromate or chromic anhy- 
dride. It is used as a pigment for paints and for the coloring 
of glass and enamel. 

CHROMIUM ACETATE. This compound comes on the market 
as a neutral or basic salt. It may be prepared by the same 
process as described for aluminium acetate, or it may be prepared 
from sodium dichromate and acetic acid in the presence of a 
reducing agent. 

CHROMIUM CHLORIDE. By passing a current of chlorine 
over a heated mixture of chromium oxide and charcoal the chro- 
mium chloride sublimes in violet crystals. It is used as a mordant 
in calico printing and to a limited extent in tanning. 

Chromium Sulphate. This is obtained by dissolving 
chromium hydroxide in sulphuric acid. It forms a violet or green 



ELEMENTS AND INORGANIC COMPOUNDS 133 

solution according to the temperature employed. It has exten- 
sive application as a mordant and in the basic condition is used 
in the manufacture of chrome-tanned leather. 

Chrome Alum. The compound Cr 2 (S04)3, K2SO4, 24H 2 
is obtained as a by-product in many operations where a mixture 
of potassium dichromate and sulphuric acid is used as an oxidizing 
agent. It is used as a mordant, and in certain chrome tannages. 

CHROMIC ACID. This compound, also known as chromic 
anhydride, is produced by acting upon a dichromate with sul- 
phuric acid. The red lustrous needles produced are separated 
from the concentrated solution, dried as rapidly as possible and 
preserved in a well-stoppered bottle. The anhydride is a very 
strong oxidizing agent. 

Potassium Dichromate. The material which is used to 
furnish the chromium is chrome iron ore or chromite. The ore is 
finely pulverized and mixed with lime and sodium carbonate. 
A small amount of calcium carbonate is usually added, as the 
carbon dioxide liberated renders the mass porous. This mixture 
is heated in a reverberatory furnace in the presence of a strong 
current of air. At the end of the reaction the mass consists of 
a mixture of calcium chromate, sodium carbonate and ferric oxide, 
which, being lixiviated, yields sodium chromate, insoluble calcium 
carbonate and ferric oxide. The solution is neutralized with 
sulphuric acid, which precipitates the alumina and silica. It is 
then filtered and evaporated. When the concentration reaches 
a specific gravity of 56° Be., the requisite amount of sulphuric 
acid is added, converting the chromate to dichromate: 

2Xa 2 Cr04+H2S04 = Na2S04+Na2Cr207+H 2 0. 

Most of the sodium sulphate is precipitated by this treatment 
and may be separated by filtration. The solution is then con- 
centrated to 60° Be., when more sodium sulphate separates, and 
on allowing it to stand the sodium dichromate crystallizes. 
From this sodium dichromate the potassium salt is obtained by 
double decomposition. The workmen must avoid breathing the 
dust or vapor containing chromates, as they attack the cartilages 
of the nose and throat. 

The residue of chromium oxide from alizarine manufacture is 
utilized in preparing dichromate. It is mixed with lime and 
molded into bricks, which are subsequently calcined in a current 
of air. In this treatment calcium chromate is formed, which may 



134 ELEMENTS OF INDUSTRIAL CHEMISTRY 

be converted into the potassium salt by treatment with potassium 
carbonate. 

Potassium dichromate forms large orange-colored crystals, 
melting at 400° C. and decomposing at a red heat into 0263 and 
K2Cr04. It is used in making chrome yellow and GuigneVs green, 
as a discharge, in bleaching oils and fats, in chrome tannage and as 
an oxidizing agent. 

SODIUM DICHROMATE. The manufacture of this com- 
pound has been given above. On account of its cheapness it 
has to a large extent replaced potassium dichromate. It is very 
deliquescent, but if dried at 200° C. it loses water of crystalliza- 
tion and becomes anhydrous, in which condition it is no longer 
deliquescent. It is more soluble than the potassium salt and 
is used for the same purposes. 

COBALT. This metal is found in nature as the sulphide. It 
is obtained electrolytically and forms both cobaltous and cobaltic 
salts. It is used as a drier for paint oils and for coloring glass. 

COLUMBIUM. This element occurs in the mineral columbite. 
The oxide forms salts with the alkalies. 

COPPER. This element is sometimes found native, but is 
usually obtained from the minerals chalcopyrite, malachite, and 
azurite. The ores are roasted to drive off the sulphur or other 
volatile matter when the copper oxide remains. The oxide is then 
reduced in a cupola or puddling furnace with carbon and a siliceous 
flux, and transferred to the converter. The black copper is then 
usually further refined electrolytically. The electrolytic porcess 
gives a very pure product and is much used in this country. 

Copper has a bright red lustrous color. It is fairly hard, but 
at the same time is ductile and flexible. It is easily drawn into 
wires and finds extensive application in electrical installations, 
being a good conductor of the current. It is used in the manu- 
facture of cooking utensils and for kettles and evaporators for 
chemical use. As an alloy metal it is used extensively, some of 
the principal alloys which contain it being brass, phosphor-bronze, 
statuary-bronze, German silver, silico-bronze, and coins. 

COPPER OXIDE. The oxide is obtained by heating the metal, 
the hydroxide, the carbonate or the nitrate to dull redness. It 
readily gives up its oxygen to organic matter when heated in 
contact with it, for which reason it is employed in organic analysis. 
Commercially it is used as a desulphurizing agent in petroleum 
oils. It is readily soluble in mineral acids, producing salts which 
have more or less practical application. 



ELEMENTS AND INORGANIC COMPOUNDS 135 

COPPER SULPHATE. This compound is also known as 
blue vitriol and as Milestone. It is obtained as a by-product in the 
parting of gold and silver by the action of boiling concentrated 
sulphuric acid, the silver being dissolved as sulphate. The 
metallic silver is recovered by precipitating it with metallic copper. 
Copper sulphate may be produced by treating scrap copper with 
a spray of dilute sulphuric acid in the presence of air. 

Copper sulphate forms blue crystals, which are soluble in 
water. Heated to 240° C. it loses its water of crystallization 
and becomes a white anlrydrous powder with a very strong 
affinity for water. Blue vitriol is used as a mordant, in the prepa- 
ration of insecticides and in germicides. 

ERBIUM. This is one of the rare elements and has no general 
practical application. 

FLUORINE. This element occurs in nature in the mineral 
fluorspar. It is a slightly greenish-yellow gas. It is one of the 
most active of the elements and combines directly with hydrogen 
even in the dark. It attacks all metals except gold and platinum 
and immediately decomposes most organic compounds. The 
element has no practical applications at present, although hydro- 
fluoric acid is used for etching on glass. 

GADOLINIUM. This is one of the rare elements and at present 
has no practical applications. 

GALLIUM. This is another of the rare elements. It is a 
soft metal which may be cut with a knife. With aluminium 
it forms a liquid alloy which will decompose water. 

GERMANIUM. This is one of the rare elements belonging to 
the same group as tin and lead. It has no practical application. 

GLUCINIUM. This is a very rare element and occurs in the 
emerald and beryl. 

GOLD. This precious metal is usually found in the free state 
and is very widely diffused through the earth's crust. The quan- 
tity, however, is so small that it pays to recover it only where 
the deposit is fairly large. The oldest method of recovering the 
metal was by levigation, but this was later replaced by the amal- 
gamation process, which consisted in combining the gold with 
metallic mercury. In recent years the cyanide process is the one 
most largely employed. With this method even low-grade ores 
can be worked at a profit. The finely ground ore is treated in 
tanks with a very dilute solution of sodium or potassium cyanide. 
The extraction is carried out in a battery, so that the ore may 
receive several applications starting with the strongest cyanide 



136 ELEMENTS OF INDUSTRIAL CHEMISTRY 

solution and ending with water. In this treatment the compound 
2KAu(CN)2 is formed. From the cyanide solution the gold is 
precipitated by adding zinc or aluminium shavings. The sludge 
is then filter pressed, dissolved and purified electrolytically. 

Pure gold is a lustrous yellow metal, soft, ductile and malleable. 
It is employed in the arts in the form of leaf for gilding and to a 
certain extent in chemical technology. For jewelry and coins it 
is always alloyed with copper. Gold forms both aurous and 
auric compounds. 

HELIUM. This occurs as one of the rarest of the elements 
on the earth's surface. It exists in certain uranium minerals and 
in the air to the extent of 0.0005 per cent. It is absolutely 
inactive. 

HYDROGEN. This element is found free in nature in very 
small quantities. Next to oxygen and silicon, however, in com- 
bination it is the most abundant of the elements, being 1 1 per cent 
of the weight of the water and a constituent of all organic bodies. 
When pure it is a colorless, tasteless odorless gas. Mixed with 
air or oxygen and ignited it combines with explosive effect. In 
the laboratory it can be produced by acting upon zinc with dilute 
hydrochloric or sulphuric acid, or by electrolysis and other simple 
means. 

Many methods have been proposed for the commercial pro- 
duction of hydrogen, among which may be mentioned : the action 
of acids on metallic iron; the action of caustic soda upon scrap 
aluminium; and the separation of the hydrogen formed during 
the manufacture of water gas. For the production of large quan- 
tities, however, the electrolytic processes have met with the great- 
est success. By properly arranged cells the hydrogen is collected 
at the negative pole, while the oxygen is obtained at the positive 
pole. The gas is employed for inflating balloons; for the oxyhy- 
drogen flame; and recently for the hydrogenation of oils. 

HYDROGEN PEROXIDE. This is prepared by the action of 
dilute acids on barium peroxide. A mixture of the peroxide and 
water of the consistency of a cream is prepared; this is added 
slowly to cold dilute phosphoric acid, the temperature of which 
should not rise over 15° C. After the proper amount has been 
added the precipitate of barium phosphate is allowed to settle 
and the clear liquid decanted. It is best to have the acid in 
slight excess, as the solution is less liable to decompose. 

Peroxides are strong oxidizing agents. Hydrogen peroxide, 
however, acts as a reducing agent in the presence of certain 



ELEMENTS AND INORGANIC COMPOUNDS 137 

oxidizing substances, in which the oxj'gen is closely linked. It 
is used in the bleaching of silk, wool, hair, feathers and ivory. 
It is a powerful antiseptic and is used in surgery and to prevent 
processes of fermentation. 

HYDROCHLORIC ACID. Hydrochloric acid occurs in nature 
as a constituent of volcanic gases, and is also found dissolved in 
water. In the manufacture of hydrochloric acid a chloride, 
either a natural salt or a waste product from some industrial 
operation, is used. 

This acid was known to the ancients, and was made by them 
by fusing salt with green vitriol. It was only known in solution 
and the gas was not known until the time of Priestley. In the 
early days of the alkali industry the hydrochloric acid, a waste 
product formed in the production of sulphate, was a great nuisance, 
and caused the manufacturer trouble, as it would destroy vege- 
tation for some distance around the plant. To prevent this 
stacks were built to the height of 500 ft., so as to dilute the acid 
va ors: but this only served to widen the circle of destruction, 
which extended over a mile and a half from the works. Then 
they conducted the gas into underground cisterns and channels, 
absorbing the gas in water and discharging it into the nearest 
water course. This killed the fish and gave an acid water which 
would corrode the metal parts of ships. Then came the economic 
absorption by water and the utilization of the acid formed in the 
production of chlorine, which was consumed in the bleach manu- 
facturing industry. Thus, the production of bleach was a natural 
outcome of the alkali industry, utilizing the ^_^ 

waste acid from the salt cake apparatus. In 
this country hydrochloric acid is the principal 
product of the action of sulphuric acid on salt, 
and the sulphate is of secondary consideration. 
In England the method of condensation is by Ft*4~f H^T? 
the use of coke towers, the acid vapors rising 
through a tall, narrow tower packed with coke, 
and meeting a stream of water which flows 
down from the top. In Europe a train of 
earthenware Woulff bottles, Fig. 63 (bom- f ig . 53. 

bonus), is used. In this country a combina- 
tion process is generally employed, the gas first passing through 
a train of the Woulff bottles, and then into a coke tower. The 
water which enters the top of the coke tower flows through the 
Woulff bottles, and the strong hydrochloric acid collected from 



w 



138 ELEMENTS OF INDUSTRIAL CHEMISTEY 

the first bottle. As the gas should be as cool as possible before 
it enters the condensers, long cooling pipes are introduced between 
the furnaces and the condensers. 

Purification. Manufacturers have found it more profitable to 
make pure acid from pure new material than to purify crude acid. 
Sulphuric acid is removed by adding to the acid, as it comes 
from the absorbers, ground barium carbonate, allowing to settle 
and then decanting. Arsenic is removed by washing with coal 
o;l in a tower between the furnace and the absorbers. 

One method of purification consists in running the crude 
hydrochloric acid in a thin stream into hot vitriol. The gaseous 
acid driven out is passed through lead pipes and absorbed in 
pure water running through lead towers packed with pure quartz, 
or well-washed coke. The sulphuric acid, being concentrated 
by heating, can be used over again. 

Uses of Hydrochloric Acid. Hydrochloric acid is used in 
" pickling " iron for tinning, in the making of chlorides and 
chlorine, in the production of glue, in the preparation of fatty 
acids from lime soap, and for various other purposes. 

INDIUM. This is one of the rare elements and is of no com- 
mercial value. 

IODINE. The chief sources of iodine are the mother liquors 
from the refining of Chilean nitrate of soda and the ashes of sea- 
weeds. About 500 tons per annum are produced from the 
former source and 200 from the latter. 

The nitrate mother liquors contain up to about 25 per cent 
sodium iodate. The iodine is liberated by the addition of sodium 
sulphite and acid sodium sulphite (from SO2) in calculated 
amount. 

2NaI0 3 +3NaS0 3 +2NaHS0 3 = 5Na 2 S0 4 +I 2 +H 2 0. 

The iodine is filtered off and purified by sublimation in cylin- 
drical iron retorts with stoneware receivers, or by distillation 
with steam. 

The ashes of seaweeds contain iodine in the form of sodium 
iodide. The ashes are lixiviated with water and the iodide sepa- 
rated by fractional crystallization. The iodine is then separated 
from the iodide solution by the action of chlorine, sometimes 
generated within the solution by the action of muriatic acid on 
manganese dioxides. 

2NaI+Cl 2 = 2NaCl+l2. 



ELEMENTS AND INORGANIC COMPOUNDS 139 

Iodine and iodine compounds have very valuable thera- 
peutic properties. Iodine is used in the aniline color industry, 
in the manufacture of iodoform, and in the production of 
pure potassium iodide, which is largely used in niedicine and 
photography. 

IRIDIUM. This element occurs in very small quantities. 
It is not dissolved even by aqua regia and for this reason is used 
as an alloy with platinum in. the manufacture of crucibles which 
will resist chemical action. The alloy usually contains about 
90 per cent of platinum and 10 per cent of iridium. It is also 
used on the tip of the more expensive gold pens. 

IRON. Iron is a metal and one of the commonest of the 
chemical elements on the earth's surface. From the magnetism 
of the earth we may also infer that its interior is probably an iron 
ball, and that the supply is limitless provided we can get at it. 
The most important chemical properties of iron from a practical 
standpoint are: First, its liability to oxidation in damp air (i.e., 
rusting); second, the ease with which its oxides (ores) are 
reduced at all temperatures above 500° F. (260° C), and third, 
its very powerful chemical affinity for carbon. 

Its most important physical properties are its strength, 
magnetism, and ability to become hardened and to retain a dur- 
able cutting edge after appropriate manufacture and treatment. 
In these three properties it can be made to excel all other known 
substances. Add to them its cheapness, and we can understand 
the importance of the ferrous metals to industry and to civiliza- 
tion. Another characteristic of iron which is of almost equal im- 
portance is its very unusual adaptability. To illustrate this 
briefly : Iron can be made either the strongest or one of the weak- 
est of metals; either the most magnetic or one of the non-mag- 
netic metals; one of the hardest or one of the softest; one of the 
toughest or one of the most brittle; it may have a coefficient of 
expansion with changes in atmospheric temperature varying 
from almost zero to a maximum, and it may be given a combina- 
tion of some of these different properties at will, according to 
the purpose for which it is to be fitted in service. And most of 
these variations are brought about by changing the amount of 
foreign elements by less than 5 per cent of the mass, or by giving 
it a different heat treatment, or by both together. 

Ores. The chief ores are the oxides, Fe203 and Fea04- In 
only a few localities is the carbonate important. Unless the pro- 
portion of iron is at least 35 to 45 per cent, the ore cannot be 



140 



ELEMENTS OF INDUSTRIAL CHEMISTRY 




Cross Section through Blast Furnace 

Fig. 64. 



ELEMENTS AND INOEGANIC COMPOUNDS 



141 



smelted with profit, except where the cost of mining plus mechan- 
ical concentration is low. 

Blast Furnace. Over 95 per cent of all the iron ore treated 
goes into the blast furnace, where it is smelted with coke and pre- 
heated air, and a relatively impure grade of metal, known as pig 
iron, is produced. The modern American blast furnace conforms 
in a general way to the lines and dimensions of Fig. 64. A column 
of coke fills the bodv of the furnace from the bottom of the hearth 



Sfotk \j0 4S0'f. 
L'ine 



Tuyeres 



(I) 2Fe z 3 + SC0*7C0 2 t4FefC(Begins) 
(2)2 " + C0 *2F e O + C0 2 +Fe 2 2 " 
S7S'(3) FetCO z *FeO + CO Begins 
750* (Q Fe 2 2 +ZC • 2Fi t 3C0 



I025°(4) CtCO^ = 2C0 (Rapid) 
1100' Deposition of Carbon Ceases 
1300 "(7) FeQ*C -- Fe + CO (Begins) 
U7 ro<7> FeOtC =Fe + CO (Complete) 
*'* (8) CaCOj = CaO*C0 2 

I850°(4) CtCOi -200 (Prey a, is) 



SO ZOSO? 

go ino'F.) 



'iilo'tA 



(9)5I0 2 +2C = 5/ t2C0 
(10) FeS i-CaOtC* CaS tFetCO 
(//> Mn0 2 t2C = Mn + ZCO 
02)P 2 2 tSC - 2P + 5C0 



Fig. 65. 



to the top of the bosh (see Fig. 66), and above this are alternate 
layers of coke and iron ore, together with an appropriate flux, 
which is generally limestone. 

The preheated air, at a temperature of usually 800 to 1200° 
F. 425 to 650° C.) and at a pressure of about 15 lbs. per square 
inch, enters through the tuyere pipes at the top of the hearth, 
combines with the fuel and creates a volume of intensely hot 
reducing gases, which pass up through the interstices of the 
charge, melting, heating and reducing the ore which it meets 
and finally passing out at the throat of the furnace. The tempera- 



142 



ELEMENTS OF INDUSTEIAL CHEMISTEY 



tures at different points in the furnace and the various reactions 
which take place are shown in a general way in Fig. 65. Below 
the top of the bosh the fuel is the only material not in liquid 
form. The iron, containing about 3.50 to 4.50 per cent of carbon 
and varying amounts of silicon, sulphur and other elements, 
according to the reactions of the smelting zone, collects in the bot- 
tom of the hearth, and on top of it the cinder, consisting of the 

impurities in the ore together with 
the ash of the coke and the lime, 
magnesia and impurities of the flux. 
All sulphur which is brought to the 
condition of CaS goes into the cin- 
der, and all that in the form of 
« FeS goes into the iron. With this 
exception the cinder contains all the 
oxidized materials and the metal 
all those in reduced condition. 

The cinder, because of its low 
specific gravity, floats on top of the 
metal and is drawn off about fifteen 
times in twenty- four hours and dis- 
posed of. The metal is tapped out 
of the bottom of the furnace about 
every six hours and is either cast 
in the form of pigs (Fig. 67) or 
transported to a nearby steel mill 
in the liquid form. 

Because of its impurity and 
therefore its friability, pig iron cannot be worked or wrought. 
Many millions of tons per year are used in the form of iron cast- 
ings, and the remainder purified. The purification consists in 
oxidizing the carbon, silicon and some other impurities. 

Electric Iron and Steel. Electricity may be used as a source 
of heat in the smelting of either iron or steel, and in localities 
remote from fuel supply and adjacent to other cheap sources of 
power, experiments of this nature have been made with commer- 
cial success. They have excited a great deal of interest, although 
the volume of production has not yet attained relative importance. 
It is 'believed, however, that electric smelting will give a cheaper, 
and a higher grade of steel than the crucible process, and impor- 
tant developments in this field have already begun. Electric 
furnaces are also the only means of producing some of the " ferro- 




Lcgcod i -^ Lumps o 



Layer of Molten Slag. 

Ltjrftr oi Mofeto Ira., 



Fig. 66. 



ELEMENTS AND INORGANIC COMPOUNDS 



143 



alloys" because sufficient temperature cannot be otherwise 
obtained. 

FERROUS ACETATE. This is prepared by adding lead or 
calcium acetate to a solution of ferrous sulphate. An impure 
product, known as " black iron " or " iron liquor," is made by 
adding scrap iron to crude pyroligneous acid. Its principal use 
is as a mordant in leather dj^eing and in calico printing. 




Fig. 67. 



FERROUS SULPHATE. This compound, also known as cop- 
peras and as green vitriol, is obtained largely as a by-product 
from the pickle used in cleaning iron castings and iron wire. 

The solution of ferrous sulphate obtained is concentrated by 
application of heat to the surface of the liquid, which thus pre- 
vents oxidation. The concentrated solution is allowed to crystal- 
lize on wooden rods. The crystals of ferrous sulphate effloresce 
in the air and become more or less oxidized, basic ferric sulphate 
being formed. Recently the evaporation has been carried out 



144 ELEMENTS OF INDUSTRIAL CHEMISTRY 

in multiple effect vacuum paus and the sulphate separated in a 
granular form by rapid cooling and agitation. It is soluble in 
about 1§ parts of water. Ferrous sulphate finds its most impor- 
tant use as a mordant, as a disinfectant, in the manufacture of 
ink, Prussian blue and red oxide. 

FERROUS SULPHIDE. On melting iron and sulphur together 
a black compound, FeS, results. It is used as a source of hydro- 
gen sulphide. 

FERRIC OXIDE. This compound occurs in nature in various 
minerals, or it may be prepared artificially by the rusting of iron. 
The natural product serves as an ore for the production of iron 
and steel and in some of its forms is of value as a pigment. The 
artificially prepared oxide is obtained in various shades, depending 
upon the method of preparation, and is used almost exclusively 
in the manufacture of paints. 

FERRIC CHLORIDE. This compound is obtained by the 
oxidation of ferrous chloride with nitric acid or by passing chlorine 
through a solution of ferrous chloride. It is used in the chlorina- 
tion of copper and silver and as a mordant in dyeing. Some- 
times it is used for the purifying of effluent water. 

FERRIC SULPHATE. This may be prepared by the weathering 
of pyrites in the presence of sulphuric acid. It may also be made 
by adding sulphuric acid and nitric acid to a solution of ferrous 
sulphate. Its principal use is as a sewage precipitant. 

FERRIC NITRATE. By treating scrap iron with an excess of 
nitric acid (sp.gr. 1.3) and evaporating the solution, colorless 
crystals are obtained. By adding ferric hydroxide to this solu- 
tion a basic nitrate is obtained. This basic nitrate is used in 
silk dyeing and weighting and for coloring buff on cotton. The 
usual form of " nitrate of iron " consists of basic sulphate of iron 
containing oxides of pitrogen. It is used in silk dyeing. 

KRYPTON. This is one of the rare elements of the atmosphere, 
being present to the extent of one part in one million. It has a 
characteristic spectrum and is noticed especially in the aurora 
borealis. 

LANTHANUM. This element occurs as a rare oxide in mon- 
azite. When the oxide is heated it gives off a very intense white 
light, which has led to its practical application, together with 
other rare earths, in the manufacture of gas-light mantles. 

LEAD. This element is found abundantly in nature as the 
mineral galena, and to a smaller extent in various other minerals. 
There are many methods in vogue for obtaining the metal, but 



ELEMENTS AND INOEGANIC COMPOUNDS 145 

the one most commonly used in this country is to first roast the 
ore in a reverberatory furnace with a silica flux; the mixture of 
oxide and silicate thus obtained is transferred to a cupola furnace, 
where it is heated with coke, lime sometimes being added. The 
lead thus formed is drawn off from time to time and run into 
molds, giving the product known as pig lead. 

Pure lead is of a bluish-gray color, is soft and ductile. On 
heating in the air it readily oxidizes. It is not attacked by 
sulphuric acid. Nitric as well as many organic acids, however, 
dissolve lead very rapidly, forming lead salts, all of which are 
very poisonous. 

Lead is used very extensively in chemical technology, espe- 
cially for building of lead chambers and other equipment em- 
ployed in the manufacture of sulphuric acid. It is used for 
making small pipes, small shot, in storage batteries and a con- 
stituent of many alloys. One of its principal applications is in 
the manufacture of lead pigments. 

Lead Suboxide : Pb 2 0. This is a black powder which readily 
oxidizes to the higher form. 

LEAD OXIDE: PbO. On heating metallic lead or residues 
remaining from the manufacture of white lead, & reddish-yellow 
powder is obtained which is commercially known as litharge. 
This material finds extensive application as a drier in paint oils, 
in the manufacture of rubber goods, and as the raw material for 
making a large number of lead salts. 

LEAD DIOXIDE: Pb0 2 . This compound, also called lead 
peroxide, is obtained by treating red lead with nitric acid. It is 
used extensively as an oxidizing agent and to some extent in the 
manufacture of matches. 

MINIUM: Pb.^O^ This compound, also known as red 
hnch is prepared by heating litharge in a reverberatory furnace 
to a temperature of about 450° C. or by heating a mixture of 
litharge and sodium nitrate to a dull red heat. It is applied in 
the form of a paint as a protective coating for steel and iron 
structures, for painting machinery, in the manufacture of glass, 
and in the preparation of storage batteries. 

LEAD CARBONATE. This material is obtained in both the 
neutral and basic condition and is discussed in Chapter VIII. 

LEAD CHLORIDE. This is a white crystalline powder obtained 
by adding hydrochloric acid or sodium chloride to a soluble lead 
salt. 

LEAD NITRATE. By dissolving litharge in dilute nitric acid 



146 ELEMENTS OF INDUSTRIAL CHEMISTRY 

and evaporating to a small volume colorless crystals of lead nitrate 
are produced. By treating with an excess of litharge the basic 
nitrate is formed. 

LEAD SULPHATE. This compound is formed by adding sul- 
phuric acid or a sulphate to a soluble lead salt. It is also dis- 
cussed in Chapter VIII. 

LEAD SULPHIDE. This compound may be prepared by 
adding a soluble sulphide to a lead salt. It occurs in nature as 
the mineral galena. 

LITHIUM. This metal may be obtained by electrolysis of 
the fused chloride. It is a soft metal with a silvery luster and hav- 
ing a specific gravity of 0.59 is the lightest known metal. In 
the form of carbonate and salicylate it is much used in 
medicine. 

MAGNESIUM. This element occurs in the minerals mag- 
nesite, dolomite, asbestos, talc, serpentine, and in the form of mag- 
nesium salts in the Stassfurt deposits as carnallite, kieserite, and 
kainite. It is prepared in the metallic state by electrolysis of 
the fused chloride and is of a silvery white color. It is ductile 
and malleable and when heated may be drawn into wire or 
ribbon. When heated in a gas flame it takes fire, burning to the 
oxide with a very bright light, which is rich in chemical rays. 
Two parts of powdered magnesium with one part of potassium 
chlorate gives a very intense light when brought into contact 
with a spark and hence finds extensive application in flashlight 
photography. 

MAGNESIUM OXIDE: MgO. This compound is obtained by 
heating the carbonate to a very high temperature. It is used 
in medicine and also as a refractory material for furnaces which 
are required to withstand very high temperatures. It finds 
application in the Nernst incandescent electric lamp, where it 
is mixed with oxides of some of the rare earths. 

Magnesium Peroxide: Mg0 2 . This product is obtained 
by treating a concentrated solution of magnesium sulphate with 
either sodium or barium peroxide. 

MAGNESIUM CHLORIDE. This compound is obtained from 
the mother liquor of the Stassfurt salts and in this country from 
the salt brines of Michigan by evaporating to about 42° Be. 
The crystals which separate consist of about 80 per cent of 
MgCl2, 6H2O. It is used as a filler for cotton and woolen goods 
and in the preparation of magnesia cements. These cements, 
which are very hard, are known under various trade names, but 



ELEMENTS AND INORGANIC COMPOUNDS 147 

they nearly all consist of a mixture of magnesium chloride, saw- 
dust, and magnesium oxide. 

Magnesium Sulphate. Epsom salts is found in many 
mineral springs, but the most important source is Kieserite 
(MgSO.±, H2O), which is quite insoluble in water, but on standing 
in contact with water for some time it undergoes solution, becom- 
ing MgS04, 7H2O. It is also prepared from kainite (K2SO4, 
MgSC>4, MgCL?, 6H2O), and is easily obtained by action of 
sulphuric acid on the natural carbonate, magnesite. It is a 
colorless crystalline salt, readily soluble in water and efflorescent 
in dry air. It loses all of its water of crystallization at about 
230° C. 

Magnesium sulphate is used in medicine under the name of 
Epsom salts.* in the finishing of cotton fabrics and for weighting 
paper, silk and leather. 

MANGANESE. Tliis element does not occur free in nature, 
but is widely distributed in the form of ores, the principal one 
being pyrolusite. In the metallic condition it is obtained by the 
Goldschmidt process as a gray lustrous material. As ferro-man- 
ganese (spiegel) it is used in metallurgy; and in some of its 
compounds has quite an extensive application in the drying of 
oils. 

MANGANESE DIOXIDE. This compound is found in nature 
iii the mineral pyrolusite. Dissolved in cold hydrochloric acid 
it forms the chloride MnCU, which on heating breaks down into 
the chloride MnCU and CI2. This reaction is the foundation of 
the Weld on process for the manufacture of chlorine, which has 
already been described. The oxide is used for many other pur- 
poses, among which might be mentioned the manufacture of 
oxygen. 

' MANGANOUS SULPHATE. This compound is obtained by 
dissolving the carbonate in sulphuric acid. It is used in dyeing 
and for painting on porcelain. 

POTASSIUM PERMANGANATE. This compound is prepared 
by mixing together potassium hydroxide in solution with man- 
ganese dioxide and potassium chlorate, boiling vigorously and 
evaporating to a paste. The paste is then heated in a crucible 
to the point of fusion, dissolved in water and oxidized with 
chlorine or ozone. It is stated on good authority that the oxida- 
tion i< also brought about electrolytically. The permanganate 
illizes from the concentrated solution in metallic-looking 
crystals. It is fairly soluble in water, giving a purple color. It 



148 ELEMENTS OF INDUSTRIAL CHEMISTRY 

is a strong oxidizing agent for organic and inorganic substances. 
It is used for bleaching vegetable fibers and for purifying various 
gases. 

MERCURY. This is the only metal which is liquid at ordinary 
temperatures. It is found to a slight extent in the free condition, 
but is obtained almost exclusively from cinnabar. From this 
mineral, which is the sulphide HgS, it is prepared by distilling 
in a free supply of air; when the mercury distills over and is 
condensed while the sulphur burns to sulphur dioxide. 

Mercury is a silvery white liquid having a specific gravity of 
13.6. It has the property of combining with nearly all of the 
metals except iron, thereby forming amalgams which have varied 
and extensive applications. The mercury-vapor electric lamp of 
Bastian has recently found quite an extensive application. The 
lamp consists of a long tube placed horizontally and contains a 
small quantity of mercury. At each end of the tube, which is 
under high vacuum, is an electrode. By passing a current through 
the mercury it becomes vaporized; the vapor thus acting as a 
conductor gives off a very intense light. The largest amount 
of mercury is used for the extraction of gold and silver, but a 
certain amount is also required for chemical and physical appara- 
tus. Mercury forms both mercurous and mercuric compounds. 

MERCUROUS OXIDE: Hg 2 0. This compound is obtained 
by treating a mercurous salt with sodium hydroxide. It is of a 
dark brown color and readily decomposes when exposed to light. 

MERCURIC OXIDE: HgO. This oxide is produced by heat- 
ing mercuric nitrate and mercury in an iron crucible. It is of a 
bright red color and known sometimes as red precipitate. 

Mercurous Chloride. This compound, also known as 
calomel, is prepared by heating a mixture of 4 parts of mercuric 
chloride with 3 parts of metallic mercury. It is heated in an iron 
pot until a white mass is formed ; the temperature is then raised 
when the mercurous chloride sublimes. It is then further puri- 
fied by washing. 

MERCUROUS NITRATE. This is obtained by dissolving 
mercury in warm nitric acid, having an excess of mercury always 
present. 

Mercurous Sulphate. This compound is formed by the 
action of concentrated sulphuric acid on an excess of mercury. 
It is a crystalline product and only slightly soluble in water. 

MERCURIC CHLORIDE. This compound, also known as 
corrosive sublimate, is obtained by subliming a mixture of mercuric 



ELEMENTS AND INORGANIC COMPOUNDS 149 

sulphate and sodium chloride in the presence of a small quantity 
of manganese dioxide. It may also be prepared by dissolving 
mercuric oxide in hydrochloric acid. Commercially, however, 
it is made by heating mercury in the presence of chlorine gas. 
Being a violent poison it should be handled with great care. 
In very dilute solutions it is applied as an antiseptic for medicinal 
purposes; while on an industrial scale it is used for impregnating 
timber. 

MOLYBDENUM, This element occurs principally in the 
mineral molybdenite, from which the oxide M0O2 is obtained 
by roasting. The metal is obtained by heating the oxide with 
carbon in a stream of hydrogen in the electric furnace. Thus 
prepared it is a gray powder w T hich on fusing becomes silvery in 
appearance. The metal is used in manufacture of some of the 
hard steels and the oxide is used in the preparation of molybdates. 

NEODYMIUM. This is one of the rare earths and has no 
practical application. 

NEON. This is one of the rare elements and occurs in the 
atmosphere. 

NICKEL. This metal occurs principally in the mineral 
garnierite, 2(XiMg)SUOi2-2H20, from which it is extracted by 
heating with coke and a basic flux, subsequently puddling in an 
open-hearth furnace with hot air to separate the iron, manganese, 
and silicon. The crude nickel formed by this or other methods 
constitutes what is known as nickel matte and is purified by elec- 
trolytic means. 

Pure nickel has a silvery appearance, is ductile and slightly 
magnetic. It remains unchanged in the air and consequently 
is used in many alloys such as nickel coins and German siber. 
It is also much used for electroplating iron, in the manufacture 
of various utensils, for making nickel-steel and armor-plate. 
In the finely divided condition it is employed as a catalytic agent. 

NICKEL SULPHATE. This compound is produced by dissolv- 
ing nickel in sulphuric acid, forming bright emerald-green crystals. 
It i< used as an electrolyte in electroplating. 

NITROGEN. This element is found free in nature in the 
atmosphere, of which it forms about four-fifths. But in this 
case some argon and other rare elements may be obtained from 
the air by removing the oxygen present. It is also found in 
abundance in ammonia salts, nitrates, and in many organic 
substances. By heating a mixture of sodium nitrite and ammo- 
nium chloride pure nitrogen may be obtained. 



150 ELEMENTS OF INDTJSTKIAL CHEMISTEY 

Formerly nitrogen was thought to be one of the most inert of 
the elements. At present, however, this idea has been greatly 
modified, as we now have many compounds which are formed 
by direct union with the element. 

The application of nitrogen in the form of some of its com- 
pounds is a very vital factor in the production of crops. As the 
natural supply of nitrates and ammonia are becoming limited 
we have had to devise ways and means for obtaining this much- 
needed element from its inexhaustible source, the atmosphere. 

Fixation of Nitrogen. The passage of a current of air through 
an electric arc causes the combination of the nitrogen and the 
oxygen to form one of the oxides of nitrogen, which may readily 
be converted into nitric acid or into a salt of this acid. But one 
commercial plant is at present in operation for the manufacture 
of this acid from air. This is in Norway, and uses the Birkeland- 
Eyde apparatus. An arc is sprung between special terminals 
of an alternating-current circuit and forced to take a broad flat 
form by means of suitable electromagnets. Through this arc 
the air is passed, the temperature of the flame being 2500-3000° 
C. By suitable regenerative systems the gases, containing 
only 30-40 milligrams of combined nitrogen as NO per liter, are 
cooled to 1000° C. and pass thence through boilers for further 
cooling, the steam from the boilers being used for evaporation 
of the final products. From the boilers the gases pass into alum- 
inium coolers and thence to oxidation tanks — iron vessels lined 
with acid-proof stone. Here the NO formed in the arc is 
further oxidized and passes to absorption towers, where the 
nitric oxides are absorbed in water. The last tower of the series 
is fed with caustic soda in order to catch the last traces of the 
nitric oxide. The final solution contains 30 volume per cent of 
nitric acid, and the towers absorb over 98 per cent of all nitrous 
gases produced. 

Besides nitric acid and nitrate of soda the Norwegian Plant 
also produces a basic nitrate of calcium, used in the fertilizer 
industry, which is made by treating calcium carbonate with nitric 
acid, and evaporating the product to dryness. 

About 60,000 horse-power is being utilized in this industry, 
individual furnaces up to 3000 horse-power being in operation. 
The yield in the process is estimated to be about 600 kilograms 
of HNO3 per kilowatt-year. 

Cyanamide. Nitrogen is absorbed by hot calcium carbide, 
forming what is known in the trade as cyanamide. The reac- 



ELEMENTS AND INORGANIC COMPOUNDS 151 

tion involved in the absorption is a reversible one, reading as 
follows : 

CaC 2 +N 2 <=* CaCN 2 +C. 

This industry is making rapid strides, there being some fourteen 
plants in operation throughout the world, the bulk of the product 
being consumed in the fertilizer industry. 

Calcium carbide is first made from lime and carbon by the 
usual electric furnace process. This carbide is then finely ground 
and the powdered material charged into a special form of electric 
furnace, where it is kept at 1000° C. Pure dry nitrogen, produced 
either by the copper oxide or the Linde process, is then passed 
over the hot carbide and is there absorbed. Starting with a 
carbide containing 75-80 per cent calcium carbide, from 80-90 
per cent of the theoretical amount of nitrogen will be absorbed, 
the resulting product being a grayish-black mass of cyanamide, 
carbide and lime. It contains on the average 20 per cent nitro- 
gen. 

The American fertilizer manufacturers require that the 
material be freed from undecomposed carbide and free caustic 
lime before they can use it. The product is therefore hydrated 
in specially designed rotary mixing apparatus before appearing 
upon the market. A small quantity of mineral oil is added to 
assist in keeping down the dust. This hydrated oiled material 
is sold in the United States under the name cyanamide. 

OSMIUM. This is one of the rare elements and has the 
highest specific gravity (22.48) of any of the metals; it also has 
the highest melting-point and in the mass is not affected even by 
aqua regia. In the form of its oxide it has been suggested as 
an electric lamp filament, but this application has never met with 
commercial success. 

OXYGEN. Oxygen is the most abundant and important of 
the elements being found in the air to the extent by weight of 23 
per cent, in water 89 per cent, as well as in minerals, acids, salts 
and as a constituent of all animal and vegetable matter. It com- 
bines either directly or indirectly with all elements except fluorine, 
helium, and argon. In the laboratory it may be prepared in 
various ways, thus giving a colorless, odorless gas. 

On an industrial scale many methods of preparation have been 
proposed, but of these only a few have proven of practical and 
of economic value. 

Electrolytic Oxyge n. Among the processes which have recently 



152 ELEMENTS OF INDUSTEIAL CHEMISTRY 

come into use is that based upon the electrolysis of water in 
specially arranged cells. This process, it is claimed, has many 
advantages over the others, especially as hydrogen is generated 
at the same time. The equipment, however, is somewhat expen- 
sive and depends largely upon the cost of electrical power. It 
can of course be operated to greater advantage where electrical 
energy is readily available. 

Boussingault-Brin Bros. Process. In the original process 
barium oxide is heated to a dull redness in a current of air, which 
has been freed from carbon dioxide. At this temperature it ab- 
sorbs oxygen and becomes barium peroxide. When the reaction 
is completed the heat is raised to bright redness when it is dis- 
sociated into barium oxide and oxygen. The barium oxide can 
be used again and the process would be continuous if the barium 
oxide did not become glassy and hydrated. For this reason the 
process is not practical, as the reaction cannot be repeated suc- 
cessfully more than ten or twelve times. 

Thessie du Motay-Marechal Process. In this process a mixture 
of manganese dioxide and caustic soda is heated in a current of 
dry air to dull redness, sodium manganate being formed. The 
properly granulated mass is now heated to 450° C. in a current 
of steam, when the following reaction takes place : 

Na 2 Mn0 4 +H 2 = 2NaOH+Mn0 2 +0. 

To secure regularity in the reaction a small amount of cuprous 
oxide may be added to the mixture. As manganese dioxide and 
sodium hydroxide are regenerated in the second reaction the 
process is a continuous one. 

Oxygen from Liquid Air (Linde Process). The machines for the 
production of liquid air have been perfected so that its production 
has become very economical. If liquid air is allowed to evaporate 
the nitrogen passes off more readily than the oxygen. By use of 
double- walled vacuum vessels the evaporation takes place so slowly 
that most of the nitrogen escapes, leaving fairly pure oxygen. 
By this method oxygen gas containing about 10 per cent of nitro- 
gen may be obtained. 

Oxygen is used in the oxy-hydrogen blowpipe, in the manu- 
facture of blown oils, in the aging of liquors, in refining of glass, 
in medicine and in the oxy-acetylene welding process. 

OZONE. This peculiar form of oxygen was first observed by 
van Marum in 1785, who passed a current of air through an 



ELEMENTS AND INORGANIC COMPOUNDS 



153 



electric discharge. It is a colorless gas having an odor of chlorine. 
Under great pressure its color is blue and when liquefied it becomes 
a dark blue, mobile liquid with highly magnetic properties. The 
chemical formula is O3 and the molecular weight is 48. At ordi- 
nary temperatures it is relatively stable, but decomposes in 
contact with organic, or in general, oxidizable matter, and spon- 
taneously at 280° C. Ozone may be formed in various ways — 
viz., by chemical action, by electrolysis, by the electrostatic 
field, by ultra-violet rays, by radio-active elements, by incan- 
descent solids and by vaporization of water. Of the chemical 
methods, the heating of peroxides or potassium permanganate 
with strong sulphuric acid may be mentioned, but the production 
by the electrostatic field has been the only one developed com- 




Fig. 68. 

mercially . The theory of the latter is not fully understood, but it is 
probable that ionization by collision takes place with consequent 
dissociation of the oxygen, which on recombination furnishes aggre- 
gates of ions consisting of molecules with an attached extra atom. 

Machines. Ozone generators have been made in various forms. 
The essential principle of all is the juxtaposition of two, or a 
plurality of discharging surfaces so as to form a condenser with 
an air gap which may or may not be furnished with a dielectric 
element. The discharging surfaces may be smooth or armed 
with points, and if smooth they may be flat or curved. Ozonators 
without dielectrics generally possess rotating electrodes so that 
they are in relative motion with the aim of averting sparking 
which favors the formation of nitrogen oxides and the destruc- 
tion of ozone already formed. 

A representative tubular unit is shown in Fig. 68. This con- 



154 ELEMENTS OF INDUSTRIAL CHEMISTRY 

sists of a cast-iron frame with two closed bulkheads connected 
together by the ozone tubes in much the same way as in a water- 
tube boiler. Within these tubes, which are of glass, the cylindrical 
high-tension electrodes are placed coaxially. The outer tubes 
are immersed in water, which forms the ground element, while 
the inner high-tension elements are connected to the circuit by 
means of suitable contacts on a bus bar carried into the air header 
through insulating bushings. The air is introduced into the rear 
header and passes through the tubes to the front, whence it 
passes into the ozone collecting pipe. 

PALLADIUM. This is one of the rare elements and is found 
to a limited extent in combination with gold. In the spongy 
condition it absorbs hydrogen with rapidity, producing a marked 
increase in temperature. Advantage is taken of this fact in pro- 
ducing automatic gas lighters. 

PHOSPHORUS. Tribasic calcium phosphate Ca 3 (P04)2 in the 
form of bone, bone ash and mineral phosphate is the source from 
which phosphorus is manufactured. The finely ground material 
is treated with sulphuric acid (sp.gr. 1.52) in lead-lined tanks. 
This converts the tricalcium phosphate into monocalcium phos- 
phate. The clear solution is drawn off and the precipitate 
thoroughly washed with hot water. The solution and washings 
are evaporated in leaden pans to 45° Be., about 25 per cent of 
coke or charcoal added and the pasty mass dried in iron pans. 
The dry mixture is then subjected to distillation in fireclay retorts, 
usually placed in two tiers. At the start of the operation the 
monocalcium phosphate is changed to the metaphosphate, which 
in the presence of carbon forms tricalcium phosphate, phosphorus 
and carbon monoxide. The neck of the retort is passed into a 
condenser containing water, under which the phosphorus col- 
lects. By this method about two-thirds of the phosphorus in 
the phosphate is set free. 

Electrical processes are taking the place of the older methods 
for the manufacture of phosphorus. A charge of the mineral 
phosphate, coke and sand is heated in an electric furnace and 
results in a yield of about 86 per cent. 

The crude phosphorus is purified by filtration through porous 
tile, chamois skin, or canvas, this operation being carried on under 
warm water, which keeps the phosphorus liquid. It may also 
be purified by melting under a warm solution of potassium 
dichromate and sulphuric acid. In Germany it is usually puri- 
fied by redistillation in iron retorts. 



ELEMENTS AND INORGANIC COMPOUNDS 155 

Ordinary phosphorus is a vellow, wax-like solid, which melts 
at 44° C, has a specific gravity of 1.82, and distills at 269° C. 
It appears on the market in the form of sticks; which being 
highly inflammable, have to be kept under water. 

RED PHOSPHORUS. The amorphous form is prepared by 
heating ordinary phosphorus in closed iron pots to a temperature 
of 250° C. for several days, as there always remains some un- 
changed phosphorus which must be removed by treating the 
mass with boiling caustic soda or carbon disulphide. Thus 
obtained it is a reddish-brown substance, which only inflames in 
the air when heated to about 260° C. It is insoluble in water, car- 
bon disulphide and, unlike ordinary phosphorus, is not poisonous. 

Ordinary phosphorus is used in making phosphor bronze; 
while the red variety is used in the manufacture of safety matches. 

PHOSPHORIC ACID. This acid is prepared from bone ash 
or mineral phosphate by the action of sulphuric acid. The 
filtered solution is concentrated to a sirupy consistency, which 
contains about 85 per cent of H3PO4. If further heated it loses 
one molecule of water and becomes metaphosphoric acid, which 
is called glacial phosphoric acid. 

PLATINUM. This metal occurs in the natural condition as 
small granules of the sandy deposits of the Ural Mountains, 
from which it is obtained by levigation. The platinum thus 
obtained is mixed with some of the other rare metals, from which 
it is separated by aqua regia and subsequent precipitation. Pure 
placinum has a silvery appearance, is one of the noble metals and 
is not altered in the air even at elevated temperatures. It alloys 
with other metals and is affected by fused alkaline hydroxides, 
phosphorus, c} r anides, sulphides, and halogens. It is applied in 
many forms of chemical apparatus and is being used very exten- 
sively in the manufacture of jewelry. 

POTASSIUM. This element occurs abundantly in nature 
combined with various other substances. It is present in all 
soils and is necessary to the production of vegetable life. The 
principal source is from feldspar and the Stassfurt deposits. 
Germany controls the market of the world of the metal and its 
compounds. Many methods have been proposed for obtaining 
the compounds of this element from other sources, but up to the 
present time none of them has reached any commercial impor- 
tance. The preparation of the element is similar to that which 
will be given under sodium, and like sodium it forms a very 
extensive series of valuable compounds. 



156 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Potassium Carbonate. This compound, also known as 

potash and salts of tartar, is found in the ashes of wood and plants, 
beet-sugar residues and wool scourings, but the largest quantity 
is obtained from the chloride by the same methods as employed 
for the corresponding sodium salt. The use of potassium car- 
bonate is somewhat limited, especially since the introduction of 
the Leblanc process for the manufacture of sodium carbonate. 

POTASSIUM CHLORATE. If chlorine acts upon milk of lime 
at a high temperature (60 to 70° C), the chlorine being in excess, 
hypochlorite is formed only as an intermediate product, which 
immediately is converted to chlorate, the final reaction being 

6Ca(OH)2 + 12Cl = Ca(C10 3 )2+5CaCl2+6H 2 0. 

This is the reaction upon which the manufacture of chlorate 
is based. Chlorine is systematically passed over milk of lime 
in cast-iron cylinders provided with stirrers, which are kept at 
the proper temperature mainly by the heat which the reaction 
itself evolves, if the combination is allowed to proceed at a suffi- 
ciently rapid rate. The chlorine is passed over the surface of 
the lime water till most of the lime has dissolved and been con- 
verted into chlorate. Any unabsorbed chlorine passes to another 
fresh cylinder in series where it is utilized. The solution is then 
evaporated to about 1.35 sp.gr. with potassium chloride, which 
reacts, forming potassium chlorate. 

Ca(C10 3 )2+2KCl = 2KC10 3 +CaCl 2 . 

On cooling the bulk of the potassium chlorate crystallizes out. 
The mother liquors are evaporated a second and third time and 
well cooled to recover the small amount of chlorate which 
remains in solution. The crude potassium chlorate is purified 
by recrystallization, and is washed and dried in a centrifugal 
machine. 

POTASSIUM CHLORIDE. This compound occurs abundantly 
in the Stassfurt deposits, from which it is separated by crystalliza- 
tion and is the chief raw material for all potassium compounds. 

POTASSIUM CYANIDE. By fusing potassium ferrocyanide 
with potassium carbonate a change takes place resulting in the 
formation of potassium cyanide and potassium cyanate; the 
latter being mostly eliminated by the addition of carbon during 
the reaction. 



ELEMENTS AND INORGANIC COMPOUNDS 157 

Potassium Hydroxide. This compound, also known as 
caustic potash, may be prepared by adding milk of lime to a solu- 
tion of potassium carbonate. The industrial method in common 
use to-day. however, is the same as that employed for the 
sodium hydroxide. The principal use of this material is for the 
manufacture of soft and liquid soaps. 

POTASSIUM FERROCYANIDE. The oldest method of manu- 
facture consists in heating a mixture of scrap iron and potas- 
sium carbonate with organic materials containing nitrogen, 
such as horns, hoofs, hides, dried blood. The modern method 
is to fuse potassium carbonate in iron crucibles and add in small 
portions the nitrogenous material. The action is very violent, 
and must be conducted with care. After the reaction is com- 
pleted the fused mass is lixiviated to separate the ferrocyanide 
from the carbonaceous matter. The solution is evaporated to a 
sp. gr. of 1.27, when the ferrocyanide crystallizes out. As the 
first product is very crude, it must be subjected to recrystalliza- 
tion. 

POTASSIUM FERRICYANIDE, This is prepared by acting 
upon the ferrocyanide with a current of chlorine: 

K,Fe(CN) 6 +Cl = KCl+K 3 Fe(CN) 6 . 

POTASSIUM NITRATE. This compound has been known 
and used for hundreds of years. It is found in nature to a limited 
extent, but is mostly prepared from sodium nitrate by double 
decomposition with potassium chloride. Its principal use is in 
the manufacture of black gunpowder. 

PRASEODYMIUM. This is one of the rare elements and 
occurs together with the other rare earths in the monazite sands. 

RADIUM. For many years fluorescence and phosphorescence 
have been known. Some substances give off light after exposing 
to sunlight, but eventually lose the property when kept for some 
time in a dark place. Phosphorescence, as we have long known, 
can be produced by friction and through other causes. Recently, 
however, some very interesting substances have been discovered 
which emit heat and light without any outside stimulants; these 
•• radio-active " substances have been much studied during the 
past few years and the discoveries made have marked a wonder- 
ful era in the development of the science of both chemistry 
and physics. Becquerel in 1896 discovered that uraninite, or 
p>'trhblew(r, emitted radiations capable of affecting a photo- 



158 ELEMENTS OF INDUSTRIAL CHEMISTRY 

graphic plate by rays which could not be reflected or refracted. 
These rays it was also learned rendered gases good conductors of 
electricity and converted insulating materials into conductors 
of the current. Becquerel attributed these properties to uranium 
and its compounds, but in 1898-99 Madame Curie and her 
husband, Professor Curie, showed that the emanat'ons were more 
marked in the residues from pitchblends from which the uranium 
had been removed. By using enormous quantities of the residues 
they were eventually able to separate a substance a million times 
more active than uranium, to which they at first gave the name of 
polonium, but afterwards called it radium. This original radium 
of the Curies has since been shown to contain other elements, 
but it is not within the scope of this chapter to deal with all of 
the interesting points which have been developed from this 
wonderful discovery. 

Radium is an element somewhat similar to barium in its 
chemical properties, forming salts with the mineral and organic 
acids. One very interesting point is that radium is supposed 
to be a metal in the stage of decomposition, for the emanations 
which are given off have been condensed and have proven to be 
the element helium. 

RHODIUM. This is one of the rare elements belonging to 
the platinum group. It is a silvery white metal which is insoluble 
even in aqua regia. It is used in the construction of electrical 
pyrometers. 

RUBIDIUM. This is one of the rare elements and occurs in 
lithium-bearing minerals. Its properties are somewhat similar 
to potassium. 

RUTHENIUM. This is a rare element belonging to the plat- 
inum group and has properties somewhat similar to that metal. 

SAMARIUM. This element is found in monazite, but has 
no commercial applications. 

SCANDIUM. This element occurs in the same group as 
samarium and is of no commercial importance. 

SELENIUM. This element occurs in some of the Bohemian 
and Swiss pyrites and is found in the dust chambers and in the 
mud of the lead chambers of the sulphuric acid works. The 
selenium is recovered by treating the dust and mud with a con- 
centrated solution of potassium cyanide and reprecipitating with 
rrydrochloric acid. The crude selenium thus obtained is oxidized 
with nitric acid to Se02, which is then purified by sublimation. 
The metal may be obtained by reducing with sulphur dioxide. 



ELEMENTS AND INORGANIC COMPOUNDS 159 

When heated in the air selenium barns to the oxide, giving off 
an odor of rotten onions. The metal may be obtained in an 
amorphous or crystalline condition, the latter being a good con- 
ductor of electricity, the conductivity increasing with the illum- 
ination. On account of this property it finds application in 
wireless telegraphy and in the wireless telephone. Much research 
work has been conducted along applied lines, but up to the present 
time there are many difficulties still unsolved. The salts have 
been proposed as a treatment, with a certain amount of success, 
in some of the so-called incurable diseases. 

SILICON. This element does not occur in the free state, but 
in combination as silicon dioxide and as silicates it constitutes 
the bulk of the earth's crust. In the free condition it may be 
prepared in various ways: one being the heating of powdered 
silica with powdered metallic magnesium. Within recent years 
its commercial preparation by heating sand and carbon in the 
electric furnace has brought it to the front in the manufacture of 
chemical apparatus. 

WATER GLASS. Soluble glass or water glass consists of soluble 
silicates of sodium or potassium or a mixture of the two. It 
usually comes on the market as a thick sirupy liquid. In its 
manufacture a mixture of sand, charcoal and soda is heated 
together in a reverberatory furnace for eight to ten hours. The 
glass-like mass is broken up and boiled with water. The solu- 
tion obtained is filtered and concentrated to the proper con- 
sistency. 

Waterglass is used to render tissues non-inflammable, to 
protect wood and porous stone, as an addition to cheap soaps, 
to fix pigments on calico, in the manufacture of artificial stone, 
as a fixative in mural paintings, also as a cement for glass and 
pottery. 

SILVER. This metal is found free in nature and in combina- 
tion with other elements principally as the sulphide. The usual 
method of obtaining the metal depends upon the fact that lead, 
when used with the proper flux, has the power of withdrawing 
the silver from its ores. The lead buckle thus obtained is heated 
in a furnace with an excess of air, when the lead burns off, leaving 
the silver behind. Many other methods have been proposed, 
but cannot be described at this time. Pure silver has a white 
►us color. It is the best conductor of electricity known. 
It does not oxidize when exposed to the air even if heated and so 
is classed as one of the noble metals. It is used as a constituent 



160 ELEMENTS OF INDUSTRIAL CHEMISTRY 

of many alloys for jewelry and for coins. It is also used exten- 
sively for silver plating. 

SILVER CHLORIDE. This compound is found ready formed 
in nature as the mineral horn silver, or it may be prepared by add- 
ing sodium chloride to a soluble silver salt. It is insoluble in 
water, but easily dissolves in ammonia, potassium cyanide, and 
sodium thiosulphate. It is used extensively in the preparation of 
photographic papers. 

* SILVER BROMIDE. By adding sodium bromide to silver 
nitrate this compound is formed. It is applied in making the 
photographic dry plate and in gaslight papers. 

SILVER IODIDE. When sodium or cadmium iodide is added 
to silver nitrate this compound is produced. It is applied in 
the manufacture of photographic dry plates and for developing 
papers. 

SILVER NITRATE. By dissolving pure silver in dilute nitric 
acid silver nitrate is obtained. If a copper-silver alloy is used, 
the copper may be eliminated by evaporating to dryness and 
heating the dry mass to a temperature of 250° C. The copper 
nitrate is decomposed, yielding copper oxide, and as the silver 
nitrate is not affected, it may be dissolved in water and the 
solution evaporated to crystallization. It is a colorless salt, 
soluble in water, melts at 225° C. and decomposes at dull red 
heat. It is used as a cautery, in photography, in the preparation 
of indelible ink and for silvering the back of mirrors. 

SODIUM. This metal is not found in the free condition in 
nature but is widely diffused in combination with other substances 
and is especially abundant as the chloride or common salt. 

Metallic sodium has a silvery appearance closely resembling 
potassium. It is oxidized rapidly when exposed to the air and 
so must be preserved under petroleum. Sodium as a metal 
is used in the preparation of fused sodium peroxide and sodium 
cyanide. Formerly it was also used to quite an extent in the 
preparation of metallic aluminium. 

SODIUM PEROXIDE: Na20 2 . This compound is prepared 
by heating sodium to 300° C. in aluminium pans in a current of 
dry air. It is a very energetic oxidizing agent at elevated tem- 
peratures and when dissolved in water gives off atomic oxygen, 
thus rendering it of value as a bleaching agent. 

CAUSTIC SODA. This product is prepared by causticizing 
sodium carbonate with lime. The purified tank liquor, which 
must be kept at a specific gravity of 1.1, is treated with lime at 



ELEMENTS AND INORGANIC COMPOUNDS 161 

a boiling temperature. Water or dilute liquor must be added 
in order that a reverse action will not take place. In the Thomas 
process the reaction may be carried out in a concentrated liquor, 
under pressure and at a temperature between 140 to 145° C. 
The calcium carbonate is allowed to settle and the supernatant 
liquor is filtered through sand and carbon. The solution of 
caustic soda is evaporated in cast-iron kettles until all of the 
water is driven off and the alkali remains as a fused mass. The 
lower compounds of sulphur, such as thiosulphate, may be oxi- 
dized by the addition of a small quantity of sodium nitrate. For 
transportation, the fused caustic is run into sheet-iron drums, 
which are closed as soon as cold to prevent absorption of water 
and carbon dioxide. 

Caustic soda may be purified by solution in pure alcohol, 
which dissolves the sodium hydroxide, but not the carbonate. 
A still purer sodium hydroxide may be obtained by the action 
of metallic sodium on distilled water. 

There are a number of electrolytic processes for the manu- 
facture of caustic soda which are discussed under chlorine. 

Sodium hydroxide is used in large quantities in the manufac- 
ture of soap, in the manufacture of paper pulp, for mercerization 
of cotton, in the manufacture of dyestuffs, in the purification of 
mineral oils and for various other purposes. 

SODIUM CARBONATE. Before 1791 sodium carbonate was 
obtained from natural deposits and the ashes of marine plants. 
At the time of the French Revolution Leblanc brought forward 
his method for the commercial production of soda from salt. 
The process, which was introduced in 1791, held sway without 
competition until 1863, when the Solvay process (ammonia-soda) 
made its appearance. This would probably have entirely re- 
placed the Leblanc process were it not for the valuable by-product, 
hydrochloric acid, which is formed during the operation of the 
latter. At present the Leblanc process furnishes a little less than 
half of the sodium carbonate consumed. 

Leblanc Process. By the action of sulphuric acid on common salt 
sodium sulphate is obtained. The sodium sulphate is then trans- 
formed into carbonate by the action of carbon and calcium car- 
bonate: the reactions involved being represented by the following 
equation: 

2NaCl+H 2 S0 4 = Na 2 S0 4 +2HCl, 

Na 2 S0 4 +2C = Na 2 S-h2C0 2 , 
Na 2 S + CaC0 3 = Na 2 C0 3 + CaS . 



162 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Preparation of Sodium Sulphate or Salt Cake. The reaction 
takes place in two stages, viz.: 

NaCl+H 2 S0 4 =NaHS04+HCl, 

NaCl+NaHS0 4 = Na 2 S04+HCl. 

The furnace used for this purpose is described at another 
place. The first reaction takes place at a comparatively low tem- 
perature and at the back of the furnace; when it slackens the 
charge is raked forward, and is exposed to a higher heat, when 
the second reaction takes place. The sulphuric acid should be 
of a strength between 57 and 60° Be. Below 56° Be. it would 
attack the cast-iron pan of the furnace, and above 60° Be. it 
forms lumps of salt with an anhydrous coating of sodium sul- 
phate. This coating prevents the penetration of the acid, thus 
making the action irregular and incomplete. 

Conversion of Salt Cake into Carbonate. The salt cake should 
contain no sodium chloride and but little free sulphuric acid. It 
should be porous and friable, for which purpose it is exposed to 
the action of the air for two or three days. It is now mixed with 
limestone and powdered coal, the proportions indicated by Leblanc 
being : 

Sodium sulphate 100 parts 

Calcium carbonate 100 parts 

Carbon 50 parts 

In practice it is usual to use an excess of limestone and coal. 
At the end of the operation, when the temperature has reached 
about 1000° C, the calcium carbonate in excess is decomposed 
with the formation of lime and carbon dioxide. The latter, 
coming in contact with the carbon, is converted into carbon 
monoxide; the blue flame which makes its appearance indicates 
that the reaction is completed. The passage of the carbon mon- 
oxide through the mass renders it porous. The limestone should 
be very pure, as silica and aluminium would cause the formation 
of silicates and aluminates. The coal should contain little or 
no nitrogen, as this gives rise to cyanides, which react upon iron 
to form ferrocyanides and, in small quantities, cyanates. 

Black Ash. In the manufacture of black ash the mixture of 
sulphate, carbon and limestone is introduced into the back of a 
black ash or balling furnace, which is a long reverberatory furnace. 
The mixture is heated at a rather low temperature at first; then 



ELEMENTS AND INORGANIC COMPOUNDS 163 

after some time the charge is raked forward, nearer the grate, 
where the temperature is much higher, reaching 1000° C. The 
mass is stirred until it stiffens and the blue flame appears, indicat- 
ing the end of the reaction. It is now worked together into a 
ball and raked into wagons, where it rapidly solidifies. On 
exposure to the air for two or three days the small quantity of 
lime present slakes, rendering the mass friable and easier to lixivi- 
ate. The hand-worked furnace is being replaced by the revolving 
furnace. 

Good black ash is of a very dark brown or gray color with 
porous fracture. It contains about 45 per cent of sodium car- 
bonate, 30 per cent of calcium sulphide, 10 per cent of calcium 
oxide, 6 per cent, of calcium carbonate and small amounts of sodium 
silicate, sodium aluminate, sodium sulphide, sodium chloride, 
ferric oxide and coal, while very slight amounts of cyanide, 
ferrocyanide and thiosulphate are usually present. 

Lixiviation of Black Ash. When properly made, black ash 
is easily extracted by Shank's process. The material is placed 
in tanks having false bottoms, and is systematically treated with 
water. The fresh water comes in contact with the nearly 
exhausted ash and as it becomes more concentrated it meets 
the fresh ash. The lixiviation should be done at as low a tem- 
perature as possible and the ash kept covered with water to 
avoid contact with the air. In case these precautions are not 
observed, secondary reactions take place, thus reducing the 
yield of sodium carbonate. 

Purification and Evaporation of Tank Liquors. The principal 
impurities of tank liquor are caustic soda, sodium sulphide, sodium 
thiosulphate, sodium ferrocyanide, sodium ferro-sulphide and 
traces of other compounds. The liquor is allowed to clarify 
by sedimentation and is then passed through carbonating towers, 
where it trickles over porous substances and comes in contact 
with a current of carbon dioxide and air. The caustic soda 
and sodium sulphide are here converted into carbonate, the ferro- 
sulphide is decomposed, and any iron, silica and aluminium 
present precipitated. 

Paulie's Process. In this process Mn02, as Weldon mud, is 
added to the liquor and superheated steam and air are passed 
through it. Sodium sulphide is oxidized to sulphate, and any 
iron, silica, and aluminium precipitated. 

In either case the purified liquor is evaporated in cast-iron 
pans. As it becomes concentrated a crystalline powder separates, 



164 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Na 2 C03,H20, which by calcination at a red heat is converted 
to Na2C03- The mother liquor is further purified or used for 
the production of caustic soda. This liquor usually contains 
a large amount of caustic soda and sodium sulphide. 

Instead of calcining the Na2C03,H20. it may be converted 
into soda crystals (sal soda) by dissolving in hot water and 
allowing it to crystallize slowly. In this way large, nearly pure, 
crystals of Na2CO3,10H2O are formed. 

Ammonia Soda or Solvay Process. This process was intro- 
duced by Solvay in 1863, and has been worked successfully 
since about 1873. It consists in reacting upon sodium chloride 
in a cold solution with hydrogen ammonium carbonate : 

NaCl+NH 4 HC0 3 = NaHC0 3 +NH 4 Cl. 

The sodium hydrogen carbonate (bicarbonate) is calcined, which 
decomposes it into sodium carbonate, carbon dioxide and water. 
By treating the ammonium chloride formed in the first reaction 
with lime, the ammonia is regenerated. The carbon dioxide is 
derived in part from the calcination of the sodium bicarbonate and 
partly from limestone, which furnishes also the lime for the 
regeneration of the ammonia from the ammonium chloride. The 
process is more economical than the Leblanc, the product is 
purer and there is no troublesome by-products, such as tank waste. 
In conducting this process a pure concentrated brine solution 
is saturated with ammonia. The brine is contained in tanks 
with perforated false bottoms, through which the ammonia is 
forced in the form of a gas. When the brine is thoroughly satu- 
rated with the gas it is run into the carbonating tower. The 
tower consists of a cast-iron cylinder 40 to 60 ft. high and 5 to 
6 ft. in diameter. At intervals of 3 to 3J ft. there are fixed 
plates with a central opening. Over these plates are placed 
dome-shaped diaphragms, which are perforated with numerous 
small holes. The ammoniacal brine is forced under pressure into 
the carbonating tower through a pipe which enters near the 
middle of the tower. The carbon dioxide, at a pressure of 25 to 
30 lbs., is forced into the lower end of the tower and allowed 
to bubble through the many perforated diaphragms; its ex- 
pansion as it enters the tower produces a cooling effect which 
prevents any great rise in temperature. 

NaCl+NH 3 +H 2 0+C0 2 = NH 4 Cl+NaHC03. 



ELEMENTS AND INORGANIC COMPOUNDS 165 

The bicarbonate of soda being insoluble in the ammonium chlo- 
ride solution is precipitated, drawn off, filtered, washed with 
cold water and calcined in cast-iron pans. The carbon dioxide 
liberated from the bicarbonate is pumped to the carbonating 
tower, and any ammonia given off is condensed and returned 
to the ammonia stills. The gases issuing from the carbonating 
tower are also condensed to recover any ammonia which they 
contain. The temperature of the solution in the carbonating 
tower should be carefully controlled, 30 to 35° C. being the 
temperature most favorable for the action. 

The soda ash produced by the calcination of Solvay process 
bicarbonate of soda is white and usually very pure, containing 
only traces of salt and sodium bicarbonate. 

Cryolite Process. The reactions involved in this process are 
as follows: 

3XaF,AlF3+3CaC03 = Na 3 A103+3CaF2+3C02. 

The sodium aluminate resulting from this fusion is decomposed 
in an aqueous solution by carbon dioxide : 

2Xa 3 A103+3C02 = 3Na2C03+Al 2 03. 

The sodium carbonate formed by this process is very pure. 

Sodium Bicarbonate. Most of the sodium bicarbonate 
on the market is produced by the Solvay process. It is used in 
the manufacture of baking powders, soda water, and other prod- 
ucts which require a mild alkali. 

Sodium Chloride. Common salt has been known and used 
since the time of the earliest man. It is an important constituent 
of food for both man and animals. It is found in all parts of the 
world. Small amounts are present in most river waters and 
some spring waters are impregnated with large quantities of it. 
Sea water contains it to the extent of about 3 per cent, while 
the water of the Dead Sea contains about 10 per cent and that 
of the Great Salt Lake, 9.7 per cent. It is also found in large 
deposits as rock salt, where it may exist in a colorless transparent 
form or with varying grades of purity down to a marl-like mass 
which contains but little salt. The deposits that are worked 
usually consist of salt not in transparent condition, but in a white, 
gray or red massive state. When it is transparent it will split 
out in cubes, but there is no cleavage in its more impure condi- 
tions. There are many deposits of rock salt in Germany and 



166 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Austria, the most important being at Stassfurt. In Spain there 
is a bed of importance ; and in fact all countries possess some salt 
deposits. The United States leads all countries in the production 
of salt, furnishing in 1912, 33,334,808 barrels of two hundred 
pounds. Of the various States Michigan produces the largest 
quantity, in 1912 this State furnished nearly 11,000,000 barrels. 
While the output of New York is over 400,000 barrels less than 
that of Michigan, the quality makes it much more valuable. 
The value of the 1912 production was 12,597,280. New York 
has led, as far as value goes, for the last five years. Louisiana 
leads in the production of pure rock salt, but important workings 
are also found in Kansas, Colorado, and other States. Rock 
salt and brine, with few exceptions, contain so much impurity 
that for the table and for many manufacturing purposes the salt 
must be purified before use. 

Properties. Sodium chloride is a colorless, crystalline solid, 
with a specific gravity of 2.13, crystallizing in cubes often with 
hollow faces. It melts at 815° C. or 1500° F., and volatilizes 
below a white heat. There is little difference in the solubility 
of salt in hot and cold water, 100 parts of water at 0° dissolving 
36 parts of salt, while 100 parts of water at boiling temperature 
dissolve 39 parts. This fact makes it possible to separate salt 
from its impurities, as most other substances are much more 
soluble in hot than in cold water. Absolutely pure salt is not 
hygroscopic, but ordinary salt will attract moisture from the 
air, sometimes in quantities sufficient to form a paste. This is 
due to the presence of admixed calcium or magnesium chloride, 
which always accompanies salt in its deposits. 

Theory of Deposits. The salt beds always give indications of 
being the result of the drying up of salt seas. In these deposits 
the admixed salts are found in the relative order of their solu- 
bility. On the bottom are found the insoluble calcium sulphate, 
calcium and magnesium carbonates, while on the top are the 
deliquescent chlorides of calcium and magnesium, with the 
chlorides of sodium and potassium and their sulphates and the 
sulphate of magnesium intermediate in the order of their solu- 
bility. In the Stassfurt deposits sixteen different salts may be 
recognized. The problem of producing commercial salt is to 
separate it from its impurities, and this is done usually by recrys- 
tallization. 

Working of Deposit. The working of the salt deposits is 
dependent upon the purity. In Germany, Louisiana, and many 



ELEMENTS AND 1N0KGAXIC COMPOUNDS 167 

other deposits the salt is mined. Shafts are sunk and galleries 
are run, often a mile or more in length. The salt is under cut 
and then blasted down from above with low-power dynamite. 
The broken-down mass is taken to the mill and run between 
corrugated rollers. The crushed salt is screened to various 
sizes, the finer grades being blown to remove the dust. One 
Colorado deposit is in the form of a crust over an underground 
lake of brine. In working this deposit the earth is removed and 
the salt cut like ice, washed in the brine, and then crushed. In 
other deposits, as in New York, the location of the bed or the 
large quantity of admixed cla} T or earthy matter renders this 
method impractical, and the salt is removed from the ground 
by boring wells and dissolving out the salt with water. In this 
case it is important to protect the upper part of the wells with 
pipes to prevent the absorption of the brine by the surface soil. 
The brine, whether natural (sea water, spring water) or artificial, 
must now be concentrated. This may be done either by natural 
evaporation through the aid of the sun or by the use of fuel. 
A means of purifying both rock salt and brine in one process 
consists in saturating the latter with the former and then crystal- 
lizing. In warm countries, as along the shores of the Mediter- 
ranean, and in California, the sea water is collected in reservoirs 
and then exposed in shallow basins to the heat of the sun, the 
salt being removed as it crystallizes, placed in heaps and allowed 
to drain and dry. One plant in California, covering 600 acres, 
divided into seven basins, requiring fifteen miles of levees, pro- 
duces 2000 tons of salt a year. The pumping is done by wind 
mills. All of the salt is collected from the last basin. The 
season is from "Slay to October. This is so impure that it must be 
refined before it can be used for table or dairy purposes. A process 
similar to this is practiced in working the salt in Great Salt Lake. 
The water is pumped into crystallizing ponds, which are simply 
large areas, enclosed with mud banks and divided into smaller 
basins. The total area of these ponds is about two square miles. 
The crystallization is carried on from March 15th to September 
loth, after which time the liquid (" bittern ") is run back into 
the lake and the " crop " gathered. The " crop " consists of 
a layer of about 6 ins. of salt, or about 900 tons per acre. The 
brine which was run back into the lake carries with it the bulk 
of the impurities, particularly the calcium and magnesium salts, 
but the gathered salt is largely contaminated with sodium sul- 
phate. This impurity is removed by drying, as the sulphate 



168 ELEMENTS OF INDUSTRIAL CHEMISTRY 

will effloresce and be reduced to a fine powder. When this powder 
is acted upon by a current of compressed air the fine sulphate 
will be blown away, leaving the coarser salt. When this is ground 
and screened it contains about 98 per cent of sodium chloride. 
The fine material which was blown out contains about 75 per 
cent of salt; this is pressed into cakes, and is used for cattle and 
sheep. This salt is not very satisfactory for dairy purposes, 
owing to the sulphates it contains. In Norway and other 
cold* countries the sea water is concentrated by freezing the 
water in enclosed basins, then pumping out the still liquid part, 
which contains all of the salt, and evaporating to crystallization. 

Evaporation of Brine. The usual form of apparatus for 
evaporating the brine by artificial heat is a long, narrow, shallow 
pan, heated at one end and with flues running the entire length. 
These pans vary from 40 ft. to over 100 ft. in length, and from 
10 to 25 ft. in width. The salt is raked out as it forms. The 
most difficult impurity to remove is calcium sulphate, which 
collects in the form of a scale on the pan. This must be 
removed, or local superheating will result in the destruction of 
the pan. Various attempts have been made to use the vacuum 
pan in the salt-boiling industry, but on account of the separation 
of anhydrous calcium sulphate, this process has not proven success- 
ful. Another objection advanced against the vacuum boiled 
salt is that it is large grained and must be crushed before use; 
this produces much dust and consequently loss. In the boiling 
of salt, if a small quantity of fat or oil is added to the pan it pre- 
vents the formation of a crust on the surface, which would retard 
evaporation. The salt which is fished out of the pans is exposed 
to steam. This dissolves out the more soluble chlorides of 
calcium and magnesium, after which it is whizzed and dried. 
Two English patents have recently been taken out for purifying 
salt. The first heats the dry salt to fusion and allows it to 
remain in that state until the impurities settle, then the clear 
liquid is decanted. The second electrolyzes a portion of the 
brine, producing sodium hydroxide, blows carbon dioxide through 
to form carbonate, then mixes this with the raw brine, precipitat- 
ing the calcium and magnesium, filters and evaporates. Neither 
of these methods are used in the United States. 

Uses of Salt. In addition to its use for table and dairy pur- 
poses, sodium chloride is used in preparing sodium sulphate, 
sodium carbonate, and indirectly for the production of all sodium 
salts. It is used in tanning, wet extracting of copper and silver 



ELEMENTS AND INORGANIC COMFOUNDS 169 

from ores, as a glaze for common earthenware or stoneware, 
and as a food preservative. Hydrochloric acid is also produced 
from common salt. 

Some countries impose a tax on salt used for table or dairy 
purposes; commercial salt being prepared under government 
supervision and " denatured " by the addition of various sub- 
stances which would render it unfit for table use, such as Glauber's 
salt, soda ash, 4-15 per cent, soda crystals, 12 per cent, sulphuric 
acid, 2 per cent, strong hydrochloric acid, 2 per cent, ammonia 
liquor, or aniline dye. The use to which the salt is to be put 
determines which of the denaturing substances is to be used. 

SODIUM NITRATE. This compound is found in large quan- 
tities, especially in Chile. The supply, however, is becoming 
exhausted, and as the material is a very important one from an 
agricultural point of view, ways and means have been devised 
for producing it artificially by electrolytic methods. 

SODIUM NITRITE. This compound is prepared by heating 
sodium nitrate with metallic lead to a temperature of 450 to 500° 
C. It is a very important chemical and is used extensively in the 
manufacture of dyestuffs and colors. 

SODIUM SULPHATE. Sodium sulphate occurs in nature both 
in crystallized form and dissolved in water. Large deposits are 
found in Arizona, Spain, Peru, Hungary, Siberia, and the Hawaiian 
Islands. Some salt works evaporate the bittern for the produc- 
tion of sulphate, but this is as a rule contaminated with much 
magnesium. Much of this sulphate is pure enough for technical 
uses. Nearly all natural sulphate, however, contains enough 
iron to make it unfit for glass manufacture. As a usual thing 
sodium sulphate is prepared in the anhydrous state, and only a 
small proportion is converted into the crystallized form. 

The usual method of preparing salt cake is by the action of 
sulphuric acid upon salt, producing hydrochloric acid as a by- 
product. In this country, where the Leblanc soda process is 
not used, hydrochloric acid is made, and the sulphate obtained 
as a by-product. 

In the manufacture of nitric acid, by the action of sulphuric 
acid upon soda niter, the sulphate formed is NaHSO/t, which is 
of very little technical use. In most places this is considered a 
true waste product, and treated as such. If vitriol and niter 
were taken in the proportion required to produce a neutral 
sulphate, the extra cost of working and the loss by decomposi- 
tion would more than balance the value of the sulphate formed. 



170 ELEMENTS OF INDUSTRIAL CHEMISTRY 

In England it is customary to mix the niter cake with the salt 
in the salt-cake furnace and work it up in that way. This is 
done in some places in this country and the practice is growing. 
Mechanical furnaces must be used in this process. Many other 
methods have been proposed for making sulphate, but the only 
one to meet with success is that of Hargreaves and Robinson, 
which is used to some extent in Europe, but finds in this country 
limited application, due largely to the fact that Leblanc soda is 
not made here. 

By far the most important method for the production of sul- 
phate is the old method of decomposing salt with sulphuric acid. 
This decomposition takes place in two stages: first, NaCl+H2S04 
= NaHS04+HCl; second, NaCl-f-NaHS0 4 = Na 2 S0 4 +HCI. 
The first of these takes place at ordinary temperature, but the 
second requires considerable heat. The actual decomposition 
is usually accomplished in two parts of the furnace, except where 
the cylinder furnaces are used. Here the operation is complete 
in the one apparatus. The salt and sulphuric acid are mixed jn 
a cast-iron pan and gently heated, usually by waste heat, until 
the mass becomes stiff. It is then pushed over onto the bed of a 
reverberatory furnace, where it is heated until all the acid 
is driven off. In many works, instead of the reverberatory 
furnace a muffle is used, thus keeping the acid vapors and the 
furnace gas separate, and not contaminating the sulphate with 
the furnace dust, thus permitting the use of coal instead of coke 
for fuel. During the second heating the mass is worked by rakes 
and slice bars in order to insure complete action. 

Formerly the pans were made of lead, but they have almost 
entirely been replaced by cast-iron pans. The lead pans are 
still used in making salt cake for the 
plate-glass industry. The iron pans, Fig. 
69, are circular in shape, from 10 to 
14 ft. in diameter, and about 2 ft. deep. 
Fig. 69. They are at the bottom 5 to 7 ins. thick 

and on the sides 2 to 3 ins. They are 
built in the furnace and covered with a gas-tight dome made 
of firebrick, and provided with an earthenware pipe to carry away 
the hydrochloric acid. Mechanical salt-cake furnaces have been 
introduced in England, but they are objected to on account of 
the introduction of a considerable quantity of iron into the salt 
cake. These furnaces consist of flat-bottomed iron pans, provided 
with a shaft carrying plows to keep the mass thoroughly worked 




ELEMENTS AND INORGANIC COMPOUNDS 171 

up. When the reaction is complete the salt cake is raked out and 
allowed to cool. 

Salt cake contains from 93 to 99 per cent of Na2S0 4 . 

The varying quantities of impurities in salt cake, such as 
NaHS0 4 , CaS0 4 , FeS0 4 , Fe 2 3 , MgS0 4 , Si0 2 , NaCl, depend 
upon the salt used and the kind of furnace. The sulphate from 
Hargreaves's process gives a purer product, excepting its content 
of NaCl, which is high. 

Glauber's Salt In the production of Glauber's salt, the 
salt cake is dissolved in hot water, filter pressed and run into 
coolers. If the salt is desired in large crystals the coolers 
are made of heavy planking and so protected that the 
crystallization takes place without any agitation. If from 
10 to 12 per cent of soda is added with the salt cake, the 
crystals will be larger, firmer and more like soda. If small 
granular crystals are desired the hot liquid is run into large 
coolers, and when the temperature has fallen to about 30° C. 
the liquid is agitated either by a wooden paddle or by blow- 
ing compressed air through it; this gives the sulphate in the 
form of fine needles, much resembling Epsom's salt, and it was 
formerly used to adulterate and even as a substitute for that salt. 
The addition of some soda ash before crystallization serves the 
double purpose of improving the appearance of the crystals and 
precipitating the iron. A little milk of lime is also often added 
to free it from traces of iron. 

In order to get a very pure Glauber's salt, the crystals first 
obtained are freed from the mother liquor by whizzing, and are 
recrystallized. The crystallization of a batch of sulphate crystals 
takes from five to eight days in winter, and from fifteen to twenty 
days in the summer. The great change in the solubility, due to 
a slight change in temperature, makes it more profitable to push 
the crystallization during the winter and store up the material 
during the summer. 

The principal uses of sodium sulphate are soda making, glass 
making, especially window and bottle glass, and for making 
ultramarine. In the form of Glauber's salt it is used as a mor- 
dant assistant, in the production of thiosulphate, in medicine, 
especially for veterinary uses, and in the making of cooling 
mixtures. 

SODIUM SULPHITE. This compound is prepared by saturat- 
ing a solution of sodium hydroxide or carbonate with sulphur 
dioxide and then adding the same amount of sodium hydroxide 



172 ELEMENTS OF INDUSTEIAL CHEMISTRY 

or carbonate as was originally introduced. It forms large crystals, 
which are used in medicine, in photography as an antichlor, 
and is the raw material for making the sodium thiosulphate. 

SODIUM BISULPHITE. This is prepared by saturating 
sodium carbonate or sodium hydroxide with sulphur dioxide, 
and comes into the market as a powder or as a concentrated 
solution. It is used in bleaching, as an antichlor, in paper 
manufacture, in the manufacture of dyestuffs, and in chrome 
tannage. 

SODIUM THIOSULPHATE. This compound is prepared by 
boiling a solution of sodium sulphite with an excess of sulphur. 
It is used in photography, as an antichlor, and in the tanning 
of leather by the Schultz process. 

SODIUM SULPHIDE. This compound is prepared by heating 
a mixture of sodium sulphate, salt and coal to a temperature of 
about 900° C. It is used in dyeing cotton with sulphur colors, 
in the manufacture of dyestuffs, in unhairing hides and skins, 
and for denitrating artificial silk. 

SODIUM CHLORATE. Sodium chlorate is much more soluble 
than the potassium salt, and cannot be made in quite the same 
way. In the manufacture of sodium chlorate, calcium chlorate 
is first made. This is evaporated to about 1.5 gravity and then 
cooled. Four-fifths of the calcium chloride solidifies. The mother 
liquor is drained off and most of the calcium precipitated with 
sodium sulphate, a little sodium carbonate being added to remove 
the last of the calcium. The solution of sodium chloride and 
sodium chlorate is then boiled down. Most of the sodium chloride 
separates from the boiling hot solution and is removed. The 
solution is then cooled, and much of the sodium chlorate crystal- 
lizes out. Twenty per cent or so is, however, left in the mother 
liquor, which goes back into process. The separation is based on 
the difference in solubility of sodium chlorate and sodium chloride 
in hot and cold solutions. 

STRONTIUM. This is one of the less commonly occurring 
elements and is found in nature principally as the mineral stron- 
tianite. It forms a series of compounds somewhat similar to those 
of barium. 

STRONTIUM NITRATE. This compound is prepared by 
treating the carbonate with nitric acid. It is used in the manu- 
facture of fireworks for producing red light. 

SULPHUR. This is an element which has been known for 
centuries, and some of the alchemists have even described com- 



ELEMENTS AND INOEGANIC COMPOUNDS 173 

pounds of it with the metals. It is known in the amorphous, 
rhombic and prismatic conditions. It is of a yellow color, insolu- 
ble in water; slightly soluble in alcohol, ether, oils, and fat, but 
very soluble in carbon disulphide, and fairly so in petroleum 
ether. 

Sulphur is found in large quantities in Sicily and up to within 
the past few years this country has furnished practically all of 
the world's supply. The recent opening up of the Louisiana 
deposits, however, has driven Sicily sulphur from the American 
market, as we in this country are now being supplied from the 
Louisiana fields. The Sicily sulphur is a surface deposit which 
on being mined is placed in piles and heated. The molten sul- 
phur in this way runs off from the impurities and when cool is 
ready for the market. The Louisiana deposits are too deep to be 
mined, and although these rich fields were known as far back as 
1868, no method of obtaining the sulphur was devised until the 
Frasch method was discovered. In 1902 the Union Sulphur 
Company started work under the Frasch process, obtaining 
about 100 tons per day. The production, however, has steadily 
increased until at the present time several thousand tons are 
being produced daily. 

The Frasch process consists in sinking a shaft or well about 
12 ins. in diameter, just as in the case of boring for oil or salt, 
until the sulphur is reached. The well is lined with an iron pipe 
in which are three other concentric tubes lined with aluminium, 
which are driven into the sulphur. Through the largest of the 
tubes superheated water under a pressure of 100 lbs. is introduced. 
The heated water melts the sulphur, causing it to rise in the 
outer tube. The sulphur, however, being heavy, will not flow 
to the surface, so to overcome this hot air under pressure is 
caused to bubble through the sulphur, thus forming an emul- 
sion, which can easily be pumped to the surface. As the sulphur 
issues from the tube it is run into large wooden boxes, where it 
settles away from the water into an immense hard cake. The 
boxes are about 20 ft. wide by 100 ft. long, the sides being 
built as the sulphur enters, some boxes being 30 to 40 ft. high. 
When cool the planks are removed from the sides and the solid 
sulphur broken out by means of a steam shovel and loaded 
directly into cars or boats. The product is so pure that it needs 
no further refining. 

FLOWERS OF SULPHUR. By heating sulphur in a Closed 
retort it distills and the volatile product formed on passing into 



174 ELEMENTS OF INDUSTRIAL CHEMISTRY 

a cool chamber collects on the walls in the farm of fine crystals, 
which are known as flowers of sulphur. 

BRIMSTONE. During the refining of sulphur for flowers of 
sulphur much of the distillate collects on the floor of the condensing 
chamber and eventually melts again. The molten sulphur is 
then drawn off into molds, in which it hardens, thus forming 
sticks of sulphur known as brimstone. 

FLOUR OF SULPHUR. A large amount of sulphur is passed 
through grinding mills, when it is converted into a powder known 
as flour of sulphur. 

LAC SULPHUR. By precipitating sulphur from some of its 
combinations a very light-colored product results, which is filtered 
off, dried and comes into the market as lac sulphur. 

Sulphur is used to some extent in the manufacture of sul- 
phuric acid; for making bisulphites, sulphites, and thiosulphates : 
and for various other purposes. 

SULPHUR MONOCHLORIDE. To prepare this compound a 
current of chlorine is passed over melted sulphur, which is heated 
to about 130° C. Chloride of sulphur mixed with sulphur distills 
over and is purified by redistillation. It is a somewhat oily 
liquid of a yellowish-brown color, having a suffocating odor and 
boiling at 144° C. When brought in contact with water it decom- 
poses with the formation of hydrochloric acid, sulphur, sulphur- 
ous acid and a small amount of sulphuric acid. Its chief use is 
in the vulcanization of rubber and in the manufacture of rubber 
substitutes. 

TANTALUM. This is one of the rare elements and occurs 
usually with columbium. It has recently acquired importance 
due to its application in the tantalum filament for the electric 
lamp. The lamp consumes less than one-half the energy of a 
carbon filament lamp for the same candle power, 

TELLURIUM. This element occurs in small quantities in the 
natural state mixed with gold and silver. It belongs to the same 
group as sulphur and forms compounds somewhat similar to that 
element. It has at present no commercial applications. 

TERBIUM. This is one of the rare elements belonging to 
the same group as cerium. 

THALLIUM. This is one of the rare elements and has no 
commercial value. 

THORIUM. This element is found in the monazite sands, 
and in its nitrate is used quite extensively in the manufacture of 
gas light mantles. The mantle used was at first made from 



ELEMENTS AND INOKGANIC COMPOUNDS 175 

cotton or linen, but to-day is prepared from artificial silk. The 
woven fabric is dipped into a solution of the nitrate of these 
rare earths, allowed to dry, dipped again and again or until a 
sufficient quantity of the salts have been absorbed. The dry 
mantle is then dipped in a solution of collodion. The mantle 
when used is put in position on the burner, the collodion and 
fiber burnt out, thus leaving a network of the oxides, which glow 
when heated, with the characteristic intense light. 

THULIUM. This is one of the rare earth elements and has 
no practical application. 

TIN. This is a metal which has long been known and is 
found in nature as the oxide occurring in many minerals. It 
is a metal with a silvery appearance and is not changed in the 
air at ordinary temperatures. Tin is used extensively for making 
cooking utensils, for lining condensers, as tin foil, and as a con- 
stituent of many alloys. It forms both stannous and stannic 
salts. 

Stannous Chloride. The hydrated salt, SnCl 2 2H 2 0, 

is prepared by the solution of the metal in concentrated hydro- 
chloric acid, aided by moderate heat. The addition of a little 
nitric acid facilitates the reaction. The solution is concentrated 
by evaporation, cooled and allowed to crystallize. When dis- 
solved in water it undergoes partial decomposition with the 
formation of an insoluble oxychloride. It is a valuable mordant 
and is used as a weighting material for silk, and in calico printing. 

STANNIC CHLORIDE. The hydrated compound is obtained 
from the mother liquor of stannous chloride by the progressive 
addition of nitric acid; the resulting liquid is concentrated and 
the stannic chloride allowed to crystallize. The penta hydrate, 
SnCl4,5H 2 0, may be prepared by passing chlorine through the 
mother liquor from stannous chloride. Its principal use is that 
of a mordant. 

SODIUM STANNATE. The salt, Na 2 Sn0 3 ,3H 2 0, may be 
obtained by fusing sodium hydroxide and metastannic acid to- 
gether, or by boiling tin scrap with sodium plumbite. It is 
known as preparing salt, and is used as a mordant. Solutions 
of tin in sulphuric acid and oxalic acid are known in the trade 
as tin spirits, and used for mordanting. 

TITANIUM. This is one of the less commonly occurring 
metals and is found principally in the mineral titanite. As a 
metal it is used in conjunction with iron for making a very tough 
steel. As the compound potassium titanium oxalate it is much 



176 ELEMENTS OF INDUSTRIAL CHEMISTEY 

used as a fixing agent for basic colors employed in dyeing cotton 
and leather. 

TUNGSTEN. This metal is found in certain minerals, prin- 
cipally in wolframite. The free metal is obtained by the Gold- 
schmidt process by reducing tungsten oxide with aluminium 
powder. In the metallic state it is used with iron for making 
hard tungsten steel. In the colloidal form it is now being used 
extensively for making the tungsten electric lamp filament; and 
in the form of sodium tungstate as a fireproofing on wood and 
fabrics. 

URANIUM. This is one of the rarer elements and is found in 
the mineral pitchblende. Its oxide is used in producing a yellow 
fluorescence in window glass. 

VANADIUM. This metal occurs in the mineral vanadinite. 
It is used to some extent with iron in producing a vanadium steel. 
Certain of its salts are used in dyeing and printing, while its 
oxides are used in the manufacture of glass and pottery. 

XENON. This is one of the very rare elements occurring 
in the atmosphere to the extent of about one part in forty million. 

YTTERBIUM. This is one of the rare elements and occurs in the 
mineral gadolinite. 

YTTRIUM. This is a rare element also occurring in the mineral 
gadolinite. It is used in the filament of the Nernst lamp. 

ZINC. This metal usually occurs in nature as the sulphide 
and is found in many minerals. The sulphide on roasting is 
converted into the oxide of the metal and sulphur dioxide escapes. 
The oxide may then be readily reduced to the metal by heating 
with carbon in a muffle furnace. Metallic zinc has a grayish- 
white appearance. It is used in making zinc-coated wire and 
iron, the latter being known as galvanized iron. It is used in 
various alloys and has many other applications. 

ZINC OXIDE. This compound is used extensively in the 
manufacture of paint and is discussed in that chapter. 

ZINC SULPHATE. White vitriol, ZnS0 4 ,7H 2 0, is prepared 
by dissolving scrap zinc in dilute sulphuric acid. Upon evapora- 
tion a white crystalline product separates. It is used to some 
extent in calico printing and in dyeing, as a drier for linseed oil, 
as a disinfectant, and as an astringent. 

ZIRCONIUM. This is one of the rare earths and was used in 
preparing the first incandescent mantles, 



CHAPTER VII 
CERAMIC MATERIALS AND PRODUCTS 

LIME. Lime, when good, is nearly pure calcium oxide, CaO, 
or a mixture of calcium and magnesium oxides. High calcium 
limes are stronger than those containing considerable percentages 
of magnesia. They are also better suited for mortar work, as 
they slake more readily. Magnesium limes, on the other hand, 
are better finishing limes, because they work smoother under the 
trowel. Pure lime, whether magnesium or not, is snow white. 
A very small percentage, however, of certain impurities may 
give the lime a gray or yellow color. These impurities are chiefly 
iron and manganese. Through certain methods of burning the 
ash of the fuel may be introduced into the lime, causing discolora- 
tion. Woodburned lime is usually much whiter than lime burned 
with coal. 

Lime is made by burning limestone in suitable furnaces at a 
temperature sufficient to drive off all of its carbon dioxide, the 
reaction being CaC0 3 = CaO+C0 2 . Theoretically, 2350 cal- 
ories per gram of lime are required to produce this change. This 
temperature is between 600 and 900° C. If a temperature 
much above 1200° C. is employed, the lime will be partially fused 
on the outside of the lumps. This causes the lime to be very 
slow in slaking, which is undesirable, as some of it may escape 
hydration in the mortar box and later will expand, or what is 
technically termed " blow " or " pop " in the wall. This latter 
manifests itself in small blisters in the finished work. 

Intermittent Kilns. The types of kilns ordinarily employed 
in burning lime may be divided into two classes — intermittent 
kilns and continuous kilns. The intermittent kilns are primitive 
and uneconomical. They are, however, frequently used by farm- 
ers and other small producers of lime. These kilns are usually 
made of large blocks of the limestone itself, though sometimes 
brick is used. The kilns are usually located on the side of a hill 
in order that the top may be accessible for charging by wagons 
and the bottom for drawing the lime and supplying the fuel. 

177 



178 ELEMENTS OF INDUSTRIAL CHEMISTRY 

In charging the kilns an arch of large blocks of limestone is built 
2 or 3 ft. from the ground, numerous small openings being left 
in it through which the flames may pass to the interior of the 
kiln. The fire is built under the arch, and on the top of the 
latter the limestone is piled, the charge usually consisting of 
stone from 2 to 8 ins. in diameter. After the kiln is full, a fire, 
usually of wood, is started, and the temperature gradually raised 
to prevent the limestone arch from crumbling. After about six 
or eight hours the temperature is raised to a red heat and main- 
tained at this temperature for about two days. The kiln and 
contents are then allowed to cool and the lime drawn by pulling 
down the arch. There is a great waste of heat and time in these 
kilns, owing to the fact that the kiln must be cooled and reheated 
each time it is charged. Old kilns of this sort can usually be 
seen in any of the limestone farming regions. 

Continuous Kilns. Three different types of continuous kilns 
are employed: these are (1) the vertical kiln with mixed feed, in 
which the limestone and fuel are charged in alternate layers; (2) 
the vertical kiln with separate feed, in which the limestone and fuel 
are not brought into contact; and (3) the chamber or ring kiln. 

Vertical Kilns. Vertical kilns with mixed feed are very similar 
to intermittent kilns, except that they are provided with an 
arrangement whereby the lime may be drawn at regular intervals 
from below. They are also usually somewhat larger than inter- 
mittent kilns. Like the latter, they are built on the side of a hill, 
usually of limestone blocks, and are sometimes lined with firebrick. 
In charging them, first a layer of anthracite coal or coke and then 
a layer of limestone is fed into the top. Fire is started at the 
bottom and works its way up. The process of charging and 
drawing the lime is continuous. These kilns are economical and, 
for the same size kiln, yield a larger quantity of product than do 
the vertical kilns with separate feed. On the other hand, the 
lime is contaminated by ash of the fuel, and the lime burned in 
these kilns must be carefully sorted in order to discard those lumps 
to which the fuel ash has adhered. 

The vertical kiln with separate feed usually consists of a steel 
cylinder lined with firebrick. These are equipped with two fire- 
places for the burning of the fuel, which are built into the sides of 
the kiln, so that the fuel is not mixed with the stone. The hot 
gases of combustion pass from the fire-box into the kiln, while the 
ash of the fuel drops through the grate bars into an ash pit below, 
and does not mix with the lime. The kilns are usually constructed 



CERAMIC MATERIALS AND PRODUCTS 179 

with hopper-shaped cooling chamber, set below the fire-box, which 
is closed by doors at the bottom. The cooling chamber holds 
about one draw of lime. These kilns are from 6 to 10 ft. in 
cross-section, and from 40 to 50 ft. in height. They are usually 
charged by employing an incline and a cable hoist, by means of 
which the cars of limestone are drawn from the quarry to the 
top of the kilns. These kilns are sometimes provided with steel 
stacks in order to induce a better draft, as it has been found that 
the better the draft the greater facility with which the lime can 
be burned. 

Ring Kiln. The chamber or ring kiln is employed to some 
extent abroad, but has not been used in this country. It con- 
sists of a series of chambers which are built about a central stack 
and connected to the latter by flues. These chambers are alter- 
nately charged with fuel and limestone. Any chamber may be 
disconnected from the flue at will and also separated from those 
before and after it by partitions. As a chamber burns out, it 
is disconnected, the lime removed and the chamber recharged. 
As a chamber is charged it is connected with the stack and the 
flames passed through all the other chambers to this one, and thus 
to the stack. These kilns are economical of fuel, but require 
considerable labor. 

Hydrated Lime. When lime is treated with water it combines 
with the water to form calcium hydroxide, CaO+H20 = Ca(OH) 2 . 
If the lime is free from impurities, it w T ill take up 32.1 per cent of 
its own weight of water. A less amount of water than the 
theoretical quantity, however, is required thoroughly to hydrate 
lime, because of the impurities that are always found to a greater 
or less extent in all commercial limes. Until very recently, lime 
was always hydrated or slaked by the mason just preparatory 
to its use. An excess of water was always used, and the calcium 
hydroxide formed with this a wet mass called lime putty. Re- 
cently, mechanical means of hydration have been introduced 
whereby the lime is hydrated by the manufacturer with just 
sufficient water to form the hydrate, leaving none in excess. 
This hydrated lime is a fine dry powder, practically all of which 
will pass through a 100-mesh screen. It is packed in paper bags 
or cloth sacks, and will keep indefinitely. It can be stored with- 
out danger of causing fire, which is not true of caustic lime. 
Mortar made with it shows less danger of blowing or popping 
in the walls. It may be added to cement, when it makes the 
latter to some extent waterproof and more easy to trowel. 



180 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Hydraulic Lime. Limestones containing appreciable amounts 
of impurities sufficient to give the calcined product hydraulic 
properties, but insufficient to take up all the lime present, make, 
when burned, hydraulic limes. They form an intermediate 
product between ordinary lime and natural cement. These 
products range from feebly hydraulic limes to limes which harden 
quite satisfactorily under water. At one time these limes were 
manufactured to a large extent in Europe. They have never, 
however, been manufactured in any quantity in this country. 
They are made by burning limestone containing from 10 to 17 per 
cent silica, alumina and iron and from 40 to 45 per cent lime. 
Magnesia may replace lime to a considerable extent. Hydraulic 
lime slakes with water jus fas does ordinary lime, only much more 
slowly. 

GRAPPIER CEMENTS. These are obtained by grinding the 
hard cores which are obtained in the manufacture of hydraulic 
lime, and consist of that portion of the hydraulic lime which dees 
not slake when water is added. La Farge cement is of this class, 
and is imported extensively in this country, owing to its light color 
and the fact that it does not stain marble and other building stones 
as does Portland cement and natural cement. 

NATURAL CEMENT. Natural cement was at one time manu- 
factured extensively in this country. Owing to the cheapness, 
however, with which Portland cement can be manufactured, 
it is being replaced by this latter. Natural cements are produced 
by burning and subsequently grinding clayey or argillaceous 
limestones, which are natural mixtures of calcium carbonate 
and clay. These limestones usually carry from 13 to 35 per cent 
clayey matter (Si02+Al203+Fe2C>3), and often a considerable 
percentage of magnesia, which seems to be interchangeable with 
lime and to replace the latter without disadvantage. 

PORTLAND CEMENT is now considered next to iron and steel 
as our most important building material, and the production of 
this in the United States amounts to over ninety millions 
of barrels annually. Portland cement is manufactured by com- 
bining a material high in lime, such as limestone or marl, with one 
in which silica, iron oxide and alumina are the chief constitutents, 
such as clay or shale. The raw materials are intimately mixed 
by finely grinding the two. The fine powder is then subjected 
to a temperature of from 1400 to 1600° C, when a sintering or 
semi-fusion takes place and the mixture rolls up into little balls 
varying in size from that pf a walnut down to that of wheat, with 



CERAMIC MATERIALS AND PRODUCTS 



181 



an occasional larger piece and some fine sand. After cooling, these 
lumps or " clinkers " are mixed with a small amount (2-3 per cent) 
of gypsum and finely pulverized. The resulting powder is Port- 
land cement. The following diagram explains this graphically: 



LIMESTONE OR MARL 
OR CHALK 



CLAY OR 5HALE OR 
SLAG OR CEMENT ROCK 



Mixed in Proper Proport- 
ions as shown by Analysis 



Pi .1 erized tea fineness 
of 90% to 95% passing 
a No IOC Test Sieve 



Burned afo Tempera- 
ture of from 1400° C 
to 1600° C 



Pulverized toa fineness 
of at /east 92% Passing 
a No. iOO Sieve and 
75% Passing a No. 200 
Sieve 



PORTLAND CEMENT 



It is now generally agreed that Portland cement is a solid 
solution of lime in a magma of ortho-silicates and ortho-aluminates 
of lime. It is therefore impossible to ascribe to Portland cement 
any definite chemical formula. The composition of Portland 
cement, however, has a great bearing upon its physical properties. 
The conditions of manufacture, particularly as to burning and 
grinding, also influence this. The composition of Portland 
cement of good quality is usually within the following limits : 

Composition of Poetland Cement 

Limits, Per Cent. Average, Per Cent. 

Silica 20-24 22.0 

Iron oxide 2-4 2 . 5 

Alumina 5-9 7 . 5 

' Lime 60-64.5 62.0 

[Magnesia : . . . ; 1-4 2 . 5 

Sulphur trioxide 1-1 .75 1.5 



182 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Practical experience has shown that the essential elements in 
cement are lime, silica and alumina. Iron oxide is present in 
nearly all clays and shales, and hence is always present in cement. 
It has a definite advantage, in that it assists in burning and lowers 
the temperature of the latter process. Cement containing no 
iron is white, but rather hard to burn. The proportions of a 
good cement should satisfy the following ratios: 

. Per cent lime = 1 9 to 2 1 

Per cent silica + per cent iron oxide + per cent alumina 

Per cent silica 



Per cent alumina 



2.5 to 4. 



In the manufacture of Portland cement great care is taken 
to see that the composition satisfies the above. If too much 
lime is present the cement will be " unsound " — that is, in time 
concrete made from it will expand and crack. If too little lime 
is present the concrete will be low in strength and may " set " 
quickly — that is, harden before the masons have a chance to 
place it in the forms. Cement in which alumina is high is also 
apt to be quick setting, and is hard to burn uniformly. High 
silica cements are usually very slow hardening, and do not attain 
their full strength for a considerable period. Cements should 
not contain more than 4 per cent magnesia, or 1.75 per cent SO3. 
The latter is usually introduced in the form of gypsum, and is 
added to regulate the setting time of the cement. 

* The materials from which Portland cement is manufactured 
may be divided into two classes: those which supply the lime 
and those which supply the silica, iron oxide and alumina. The 
first are termed calcareous and the second argillaceous. The 
following groups show the principal materials used in the manu- 
facture of Portland cement. 

Calcareous Materials. Argillaceous Materials. 

Limestone Cement Rock Clay 
Marl Shale 

Chalk Slate 

Alkali waste Blast furnace slag 

The cement rock is an argillaceous limestone which contains 
usually between 65 and 80 per cent carbonate of lime. If it 



CERAMIC MATERIALS AND PRODUCTS 183 

contains more than 75 per cent it is necessary to add clay, shale 
or slate to it in order to make a satisfactory mixture for burning. 
If it contains less than 75 per cent it will be necessary to add 
limestone for a similar purpose. 

Limestone is usually mixed with clay or shale, marls and 
chalks with clay or shale. Blast furnace slag is used with lime- 
stone. Alkali waste (or precipitated CaCC>3, obtained from the 
manufacture of caustic soda) was at one time mixed with clay, 
but is not now employed for the manufacture of Portland cement. 

Limestones, marls and chalks which are to be used in the manu- 
facture of Portland cement should contain less than 2\ per cent 
magnesia and preferably not more than 3 or 4 per cent silica, iron 
oxide and alumina combined. Clay, shales and slates should 
all have at least 2 J and not more than 4 times as much silica as 
alumina. Exceptions to this are in the case of a high silica lime- 
stone, with which a high alumina clay may be used to advantage, 
since all that is necessary is that the mixture shall satisfy the 
requirements expressed by the above formulas for the composi- 
tion of Portland cement. 

Three processes are employed for the manufacture of Port- 
land cement — the dry process, a semi-wet process, and a wet 
process. The dry process is employed exclusively for the manu- 
facture of cement from cement rock and limestone, and also from 
limestone and shale and limestone and blast furnace slag. The 
semi-wet process is employed at a few plants manufacturing 
cement from limestone and clay. The wet process is employed 
by plants using marl and clay. 

The dry process is an American invention, is the most econ- 
omical of the three and is the one most largely employed in this 
count ry. In this process the materials are dried and mixed, 
ground to such a degree of fineness that at least 92 per cent of the 
mix will pass a 100-mesh sieve. The material is then burned in a 
rotary kiln at a temperature of from 1400 to 1600° C. The 
resulting clinker is then mixed with 2 to 3 per cent of gypsum, 
ground to pass a 100-mesh sieve and is known as Portland 
cement. 

The grinding is done in various forms of mills and many 
mechanical operations are involved. The most important stage, 
however, is the burning, and to make this clear a description of 
the rotary kiln will be found below. 

Rotary Kiln. The rotary kiln in its usual form, Fig. 70, 
consists of a cylinder from 6 to 8 ft. in diameter and from 60 



184 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



to 150 ft. long, made of sheet steel and lined with firebrick. The 
steel sheets are from \ to -^ in. thick, and are held together by 
single-strap butt joints. This long cylinder is supported at a 
very slight pitch (f in. to the foot) from the horizontal, on two 
or more tires made of rolled steel, which in turn revolve on heavy 
friction rollers. The kiln is driven at a speed of from one turn 
a minute to a turn in two minutes by a girth-gear situated near 
its middle, and a train of gears. The power is supplied by either 
a line shaft or a motor. The upper end of the kiln projects into 
a brick flue, which is surmounted by a steel stack, also lined 
with firebrick for its entire height. The flue is provided with 




Fig. 70. 



a door at the bottom, which serves not only to allow the flue to 
be cleared of the dust which accumulates in it, but also as a damper 
to control the draft of the kiln. 

The material to be burned is usually fed into the kiln through 
a horizontal water-jacketed screw conveyor, or else spouted into 
it through an inclined cast-iron pipe. When slurry is to be burned 
this is pumped into the kiln. The dry raw material is kept in 
large steel bins above the feeding device, while slurry is stored 
in vats, in order, in either case, to have on hand a constant and 
regular supply. The raw material feeding device is usually 
attached to the driving gear of the kiln, so that when the kiln 
stops the feed also stops. 



CERAMIC MATERIALS AND PRODUCTS 185 

The lower end of the kiln is closed by a firebrick hood. This 
is usually mounted on rollers, so it can be moved away from the 
kiln when the latter has to be relined. The hood is provided 
with two openings: one for the entrance and support of the 
fuel-burning apparatus, and the other for observing the opera- 
tion, temperature, etc., of the kiln, and through which bars 
may be inserted to break up the rings of material which form, 
and to patch and repair the lining. The lower part of the hood 
is left partly open. Through this opening the clinker falls out 
and most of the air for combustion enters. 

The kiln is heated by a jet of burning fuel, usually powdered 
coal, but sometimes (as in Kansas) natural gas and (as in Cali- 
fornia) fuel oil are used. The coal is blown in by a blast of 
air supplied by either a fan or air compressor. If the fan is 
used, about 20 per cent of the air necessary for combustion is 
supplied in this way. If the compressor is employed, only 5 
to 10 per cent of the air is delivered by the compressor. 

The necessary temperature of the hottest part of the kiln 
is about 1400° C, and is rarely ever less than 1600° C. To 
properly maintain this temperature, about 80 to 160 lbs. of 
fuel are required per barrel of cement, the actual amount 
depending on the coal itself, the material to be burned and 
the dimensions of the kiln. The longer the kiln, the greater 
economy it will show. Dry materials require much less coal 
than slurry. With limestone and shale mixture, and a kiln 
100 ft. long by 7 ft. in diameter, the coal consumption will 
amount to about 90 lbs. of good gas slack per barrel. A kiln 
60 ft. long by 6 ft. in diameter will, on the other hand, require 
about 110 lbs. of this material per barrel. 

Coolers. As the clinker leaves the kiln at about 2000° F., 
it is entirely too hot to grind , and must be cooled to ordinary 
air temperatures. This can be done by allowing it to lie in 
piles; but as it is a slow way of doing it, mechanical devices 
are usually resorted to. These may consist of either revolving 
horizontal cylinders or vertical stationary coolers. The former 
consist of steel cylinders provided with angle irons on their 
insides to carry the material up and drop it through the current 
of air passing through the cylinders. They are mounted on 
tires and rollers, just as are kilns and driers, and revolve at a 
speed of about a turn or two a minute. They are usually 
placed below the kiln, and the clinker falls from the kiln into 
them. The air for cooling is also drawn through them into 



186 ELEMENTS OF INDUSTRIAL CHEMISTRY 

the kiln by the draft of the latter. They thus serve not 
only to cool the clinker, out also to preheat the air entering the 
kiln. 

The upright cooler, however, is almost universally used in 
the Lehigh district. It consists of an upright steel cylinder, 
8 ft. in diameter and 35 ft. high, provided with baffle plates 
and shelves. As the clinker falls over these, it meets a current 
cf air blown in through a perforated pipe running up through 
the^ center of the cylinder^ and is thus cooled. The clinker is 
carried from the kiln into these latter coolers by means of 
bucket elevators, water being run into the buckets to keep them 
cool. This also suddenly chills the clinker and makes it brittle 
and easier to grind. 

After cooling, the clinker is ground in Griffin mills or ball and 
tube mills. In the case of the Griffin mills, it is usually found 
more economical to crush the clinker down to pea size by a set 
of rolls, before feeding to the mills. Kent mills and air sep- 
arators, and also Kent mills which grind as preparation for 
the other mills, are used to a limited extent. The clinker should 
be ground so fine that at least 92 per cent of it passes a sieve 
having 100 meshes to the linear inch. 

In order to regulate the set of the cement, since clinker ground 
alone would set very rapidly, it is necessary to add to it calcium 
sulphate in some form or other, usually as gypsu m or plaster 
of Paris. As this can be most easily mixed with the cement 
during grinding, it is the usual practice to add the retarder to 
the clinker before the latter is ground, and to grind the two 
together. The amount of gypsum or plaster of Paris used is 
usually about 2 or 3 per cent of the weight of the clinker. 

PLASTER OF PARIS. Plaster of Paris is made from gypsum 
by heating the latter to a temperature of between 212 and 400° 
F., when three-quarters of the water of crystallization of the 
gypsum is driven off, the resulting product being plaster of Paris. 

2CaS0 4 2H 2 6 = (CaS0 4 )2H 2 0+3H 2 0. 

In actual practice the temperatures employed to bring about 
this reaction are 330 to 395° F. If gypsum is heated above 
400° F., it loses all of its water of combination and becomes 
anhydrous sulphate of lime, the latter being the basis of hard 
finish plaster, floor plaster, Keene's cement, etc. 

When plaster of Paris is mixed with water it sets or hardens 



CERAMIC MATERIALS AND PRODUCTS 187 

very promptly, this change being due to absorption of water, 
forming gypsum again. 

(CaS04)2H 2 0+3H20 = 2CaS042H 2 0. 

A pure plaster of Paris will normally harden or set in from 
five to fifteen minutes after having been mixed with water. If 
the gypsum from which the plaster is made contains impurities, 
the set will be much slower than this. Plaster to be used for 
building purposes must be slow setting. For ornamental use, 
it must also be white; and since the impurities usually render 
the plaster slightly colored, it is the common practice to add 
retarders to the plaster before placing the same upon the mar- 
ket. The materials used as retarders are usually of a colloidal 
nature, such as glue, sawdust, blood, packing-house tankage, 
etc. If a very quick-setting plaster is desired, crystallized 
salts are employed, such as common salt, sodium sulphate, 
sodium carbonate, etc. 

CLAYS. This is the term applied to such natural-occurring 
earthy materials having the property of plasticity when wet, 
which on heating to a high temperature become hard and retain 
the shape of the molded article. Clay is of secondary origin, 
and, as a rule, results from the weathering of feldspathic rock, 
such as granite. When found overlying the rock from which 
it was formed it is termed primary or residual clay. When 
washed from the original bed and deposited elsewhere it is 
known as secondary clay. 

Kaolin. This term applies to the white-burning clays which 
are composed almost wholly of silica, alumina and chemically com- 
bined water, with only a very small percentage of fluxing material, 
such as iron. Their formation is principally due to the weather- 
ing of pegmatic veins, although in some cases they have originated 
from granite, quartz, and limestone. When mined they contain 
a greater or less amount of the parent rock, which is removed 
by subsequent washing. It occurs quite widely distributed in 
the United States, east of the Mississippi, while less important 
deposits are found in Missouri, Utah, and Texas. It is used in 
the manufacture of white ware, porcelain, tiles, and as a filler 
for paper. 1 

Ball Clay. These clays are white burning, but differ from 
the kaolins in that they are plastic in character. They find 
extensive application in the manufacture of white ware, being 



188 ELEMENTS OF INDUSTEIAL CHEMISTRY 

used for the purpose of giving the necessary plasticity and 
bonding power. They must be as free as possible from iron 
oxides and possess considerable tensile strength. These clays 
occur mostly in Florida, Kentucky, Tennessee and New Jersey. 

Fire clays. This term applies to such clays as are capable 
of withstanding high temperature. They owe their refractiveness 
in most part to the large amount of silica and small amount of 
fluxing agents which they contain. Fireclays vary widely 
in their physical and chemical properties, showing great dif- 
ferences in color, plasticity, texture, and tensile strength. They 
are, as a rule, light in color, ranging from gray to yellowish red. 
The deposits may be of either primary or secondary origin. 
They may be divided into plastic and flint clays, the former 
being plastic when wet; while the latter are hard and flint- 
like, even when finely ground, but they are very highly refrac- 
tory. They occur quite widely distributed over the United 
States. The principal uses of fireclays are for the manufacture 
of firebricks, retorts, furnace linings, crucibles and terra-cotta; 
while a special grade is also used for making pots and tanks 
for glass manufacture. 

Stoneware Clays. These clays differ from fireclays in that 
they produce a very dense body when heated at a comparatively 
low temperature. In many instances, however, they are very 
refractory, but must possess sufficient toughness and plasticity 
to be worked on the potter's wheel. In making stoneware it 
is usually customary to employ mixtures of clays so as to pro- 
duce certain characteristics in the finished product. Stoneware 
clays are used in the manufacture of stoneware vessels, as well 
as yellow ware, art ware, earthenware and even terra-cotta. 

Terra-cotta Clays. The clays used for making terra-cotta 
differ quite widely, although most manufacturers prefer a semi- 
fireclay. Buff burning clays are commonly used, because of the 
hard body produced on burning. Those suitable for this purpose 
are found mostly in New Jersey, Pennsylvania, Indiana and Mis- 
souri. 

Seiver-pipe Clays. The clays employed for this purpose are 
quite similar to those used in the manufacture of paving brick. 
The easily fluxing clays are of advantage here, as the higher iron 
content aids in the formation of the salt glaze with which the 
pipes are covered. Some fireclay is usually employed in the mix 
in order to retain the shape of the tube during the burning. 

Brick Clays. In making common brick, low-grade red-burn- 



CERAMIC MATERIALS AND PRODUCTS 189 

ing cla3^s are usually employed. The principal requirement is 
that the clay shall mold readily and burn hard at a comparatively 
low temperature. Owing to the market price being low it often 
happens that poor bricks, which are made from local deposits, 
are used for structural purposes where a better material should 
have been employed. Pressed brick, on the other hana, call for 
a higher grade of clay. The physical requirements here are 
uniformity of color in burning, freedom from warping, absence 
from soluble salts, with sufficient hardness and low absorption 
when burned at a moderate temperature. 

Paving-brick Clays. A great variety of materials are em- 
ployed for this purpose, although those mostly in common use 
are made from, impure shales. These shales are widely distributed. 
They should have a fair degree of plasticity and a good tensile 
strength. 

Slip Cloys. These clays contain a large amount of fluxing 
material which melts at a low temperature, forming a natural 
glaze of greenish-brown glass. 

Gumbo Clays. Included in this class are certain fine-grained, 
plastic and tough clays, which on account of their shrinkage on 
burning cannot be used for brick making. Their chief use is 
in the manufacture of railroad ballast. 

Retort Clays. These are dense burning, plastic, semi-refrac- 
tory clays, emploj^ed mostly in the manufacture of gas and zinc 
retorts. 

Pot Clays. The clays coming under this head are hard burn- 
ing and are employed in the manufacture of pots for glass making. 

Ware Clays. These clays are the same as ball clays. 

Pipe Clays. These clays are the same as sewer-pipe clays. 

Sagger Clays. This is the term applied to those clays which 
are used in making the saggers in which high-grade pottery is 
burned. 

Portland Cement Clays. In the manufacture of Portland 
cement a mixture of lime and clay is employed. They may be 
either true clays or shales. 

Paper Clays. In order to give body, weight and finish to 
certain papers, some form of clay is usually employed. The 
clay, which should be of a plastic nature and of light color, is 
mixed with the pulp in the beater engine, where it becomes en- 
meshed. 

Paint Clays. Many of the clays mix well with linseed oil and 
form a good grade of paint. The color of these clays varies from 



190 ELEMENTS OF INDUSTRIAL CHEMISTRY 

light yellow to a dark reddish brown, due to the presence of 
iron oxide and in some instances to that of manganese. The 
chief clays coming under this heading are the ochers and siennas. 

USES OF CLAY. In order to show the varied and numerous 
applications of clays the table compiled by R. T. Hill and ampli- 
fied by Heinrich Reis will be given : 

" Domestic. Porcelain (white ware, stoneware, yellow ware, 
Rockingham ware for table service and for cooking); majolica 
stove; polishing brick; bath brick; fire-kindlers." 

" Structural. Brick (common, front, pressed, ornamental, 
hollow, glazed, adobe); terra-cotta; roofing-tile; glazed and 
encaustic tile; drain tile; paving brick; chimney-flues; chimney- 
pots; door-knobs; fireproofing; terra-cotta lumber; copings; 
fence-posts.' 7 

" Refractories. Crucibles and other assaying apparatus; 
gas retorts; firebricks; glass pots and blocks for tank furnaces; 
saggers; stove and furnace bricks; blocks for fire boxes; tuyeres; 
cupola bricks; mold linings for steel castings." 

" Engineering. Puddle; Portland cement; railroad ballast; 
water conduits ; turbine wheels; electrical conduits; road metal." 

" Hygienic. Urinals; closet bowls; sinks; washtubs; bath- 
tubs; pitchers; sewer-pipe; ven bila ting-flues ; foundation-blocks; 
vitrified bricks." 

" Decorative. Ornamental pottery; terra-cotta; majolica; gar- 
den stands; tombstones." 

"Minor Uses. Food adulterant; paint fillers; paper filling; 
electric insulators; pumps; hilling cloth; scouring soap; pack- 
ing for horses' feet; chemical apparatus; condensing worms; 
ink-bottles; ultramarine manufacture; emery wheels; playing 
marbles; battery-cups; pins; stilts and spurs for potters' use; 
shuttle-eyes and thread-guides; smoking-pipes ; umbrella-stanas ; 
pedestals; filter-tubes; caster wheels; pump-wheels; electrical 
porcelain; foot-rules; plaster; alum." 

BUILDING BRICKS. There are many forms of building bricks, 
including common building bricks, pressed bricks, glazed bricks 
and enamel bricks, but as space does not permit a complete 
description of each, only the manufacture of common building 
brick will be given. The processes involved may be divided 
into the preparation of the clays, the molding, the drying and the 
burning. 

Preparation. Since only a few clays can be used directly as 
mined it becomes necessary to subject the material to weathering 



CERAMIC MATERIALS AND PRODUCTS 191 

agencies. This is done by spreading the clay over the ground in 
a thin layer of from 2 to 3 ft. in depth, and allowing it to remain 
thus exposed for a considerable period, lasting in some cases 
a year or more. In order to hasten the process, however, some 
clays are disintegrated by artificial means, for which purpose 
crushers, edge runners, disintegrators and roller mills are employed. 
The grinding is usually done on the dry clay, although in some 
cases the wet clay is used and the process is known as tempering. 

Ring Pits. These are pits about 25 ft. in diameter and from 
2 to 3 ft. deep. A heavy iron wheel is arranged by means of gears 
so that it travels in the pit and causes a thorough mixing of the 
mass. The operation lasts from five to six hours, at the end of 
wnich time the clay is ready for the brick machine. 

Pug Mills 1 These machines are of different shapes and 
capacity, but are all provided with blades which cut up the clay, 
produce a thorough mixture and pass it along to the discharge 
end. They do not take up as much room as the ring pit and are 
much more readily handled. 

Molding. The simplest form of molding consists in pressing 
the soft clay or mixture into wooden frames which have been 
dusted with sand to prevent sticking. This operation is done 
either by hand or by machine and is known as the soft-mud 
process. In the so-called stiff -mud process the clay is tempered 
with much less water. The prepared clay is forced through a 
die in the form of a rectangular bar, which is then cut into lengths 
of the brick. The machine employed for this purpose is provided 
with an auger screw and runs in a cylinder which tapers at the 
end to the size of the die. Dry pressing is sometimes done as 
well as semi-dry pressing. In either case the prepared clay is 
forced with great pressure into steel molds. 

Drying. After molding, the bricks must be dried before 
burning. This may be accomplished in several ways, the simplest 
being to spread the bricks over a smooth flat floor and allowing 
them to dry in the sun. Pallet driers are covered frames on which 
the bricks are placed as they come from the machine. Drying 
in the air has the disadvantage in that it cannot be used in 
cold or damp weather. To overcome this many brickmakers 
are employing drying tunnels. In this method the green bricks 
are placed on cars and run in at the cooler end of the tunnel 
and gradually pushed along to the warmer end. These tunnels 
are built in a variety of ways, but when possible the waste heat 
from other operations is employed. 



192 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Burning. The bricks having been thoroughly dried are placed 
in kilns and heated to a comparatively high temperature or 
" burned." The temperature and time of heating depends 
upon the kind of clay employed and the degree of hardness desired. 
The kilns may be either " up-draft ,; or " down-draft. " In the 
former system the heat from the fire passes into the body of the 
kiln and up through the ware, finally escaping at the top. The 
heat in the down-draft kiln enters at the top, passes down over 
the ware and escapes through flues at the bottom. 

Continuous or ring kilns are also employed. They consist 
of a series of chambers arranged in the form of a circle, connected 
with each other and with the stack by means of a series of flues. 
The fire is built under the chamber which is to receive the highest 
temperature ; from here the heated gases pass to the next chamber 
and so on to the freshest charge. In order to utilize the heat 
from the cooling bricks, after they have reached their maxi- 
mum temperature, the air supply to the fire is drawn through 
the chambers containing the thoroughly burned and cooling 
bricks. 

Sewer-pipe Manufacture. Most sewer-pipes are made from 
shale, which after crushing is mixed with the necessary amount 
of plastic material and made into the desired shape by a special 
form of press. The drying and burning is then carried out in a 
somewhat similar manner as that given for brick. 

Hollow Structural Material. Included in this classi- 
fication are fireproofing terra-cotta lumber, hollow blocks and 
hollow bricks. The fireproofing materials are those which are 
employed in floor arches, partitions, and wall furring for girders 
and columns. Terra-cotta lumber is a soft and porous material 
produced by mixing sawdust with the clay and subsequently 
burning it out. This being soft can be nailed the same as lumber. 
Hollow block and hollow brick are used for outside walls. 

FIREBRICKS. Most of the firebricks on the market are 
made from a mixture of several clays to which has been added 
a certain amount of ground firebrick or quartz. They are made in 
many shapes and vary greatly in hardness and their degree of 
refractory power. The burning is almost universally conducted 
in down-draft kilns. 

TILE. Under this heading comes roofing tile, floor tile and 
wall tile. They are made in a variety of ways and from a variety 
of materials. Some are made in a porous condition while others 
are colored and highly glazed. 



CERAMIC MATERIALS AND PRODUCTS 193 

POTTERY. This heading includes a great variety of prod- 
ucts ranging from the cheap earthenware, such as flower-pots, to 
the most delicate porcelain vase. In the manufacture of pottery 
there are certain operations which are common to all, but with 
the higher grades much more care and a larger number of details 
are necessarily involved- The general operation consists in the 
preparation of the raw material, tempering, molding, drying, 
biscuit burning, dipping, glost-burning, and decorating. 

STONEWARE. This class of material is made from low- 
grade plastic clay, being porous in character, red to cream in 
color and may or may not be glazed. If the object is to receive 
a glaze, it is usually developed with the body so that after 
drying the object is in a proper condition for the application 
of the glaze. Slip-clay, which is largely used for this purpose, 
melts to a brown glass at the temperature at which the ware 
is burned. Salt glazing is a very simple method and is in com- 
mon use for this kind of ware, although it is applied more especially 
to sewer-pipe. The goods having been placed in the kiln and 
the maximum temperature reached, the salt is thrown imo the 
fire. The high temperature causes a volatilization of the salt 
which on coming in contact with the clay unites with it, forming 
a glaze on the surface of the ware. In yellow ware the object 
is burned to develop the body, after which the glaze is applied 
and the ware heated a second time. 

WHITE WARE. Included in this class are those products 
having a white or nearly white body and usually glazed. Mix- 
tures consisting of kaolin, ball-clay, quartz, and feldspar are the 
materials which are employed, and these are selected with the 
idea of their white-burning qualities in view. 

PORCELAIN. Prior to the sixteenth century, this term was 
used to designate those objects made from mother-of-pearl. 
At the present time, however, the same materials are employed 
for making porcelain as those used for white ware. Great care, 
however, must be exercised in their selection and the mixtures 
so proportioned as to give a hard and translucent body. That 
in which spar is used for the flux is known as hard porcelain 
and is bluish white by transmitted light, while that fluxed in 
part with calcium phosphate, known as bone china, is yellow 
by transmitted light. 

GLAZES. For all pottery, except hard porcelain, the ware 
is first burned in the biscuit kiln, forming porous porcelain, 
then glazed and burned again in the glost-kiln. The glazes 



194 ELEMENTS OF INDUSTRIAL CHEMISTRY 

consist of mixtures of acids and bases so combined that they 
will melt to a glass at the temperature of burning. It is very 
important also that the coefficient of expansion agrees with the 
body of the ware, otherwise a defective glaze will be the result. 

GLASS. Glass is an amorphous product of fusion, differing 
widely in composition. Ordinarily it is considered as a mix- 
ture of an alkaline silicate and the silicate of one or more bases, 
the alkali being sodium or potassium, the base calcium or 
lead, while sometimes all four elements enter into its compo- 
sition. While this is true of nearly all commercial glass, it 
must be noted that at Jena and elsewhere glasses have been 
made free from alkali, that borates and phosphates have been 
substituted for silicates, and that many elements, such as zinc, 
barium, magnesium, and antimony, have been substituted for 
lead and lime, so that it is practically impossible accurately 
to define glass. 

Technically, transparent glasses are divided into lime glass 
or lead glass according to the presence of these elements. The 
term flint glass, which originally meant a pure lead potash glass, 
is now often applied to all clear transparent glass. Sometimes 
the lime glass is called lime flint or German flint. Bottle and 
window glass are impure forms of lime glass. White or "'opal " 
glass and colored glass are glasses to which materials have been 
added to produce the color effect. 

The following are the chief raw materials used in making 
glass : 

Silica. Silica is usually introduced in the form of sand, 
which may vary in purity, according to the source and care in 
preparation. The chief impurities in sand are iron, alumina, 
and organic matter. The presence of a small amount of alumina 
does not injure the glass, but iron acts as a coloring agent, pro- 
ducing a green of more or less intensity, depending on the quan- 
tity present and the state of oxidation. For the finer glass, 
therefore, a sand as free , from iron as possible is required, while 
for more common ware, such as green bottles, a much larger 
quantity is permissible. Sand from Berkshire, Mass., is prac- 
tically free from iron, while that from Pennsylvania and West 
Virginia often contains less than one-tenth of one per cent. Sand 
from New Jersey usually has a much higher iron content. 

The sand must be of uniform size, not too coarse to prevent 
reaction with the other material, not yet so fine as to cause the 
reaction to take place too violently and cause excessive foaming 



CERAMIC MATERIALS AND PRODUCTS 195 

during the melting. Natural silicates, such as feldspar, are 
sometimes used as a source of silica, because of the alumina 
and alkali which they contain. Slags from metallurgical proc- 
esses have been used for common ware with va^dng success. 

Alkali Metals. Sodium-carbonate (soda ash), produced 
either by the Solvay or the Leblanc process, is the chief source 
of soda and is obtained from the trade in a pure condition. 
Sodium sulphate (salt cake), owing to its cheapness, is also used 
in the manufacture of plate and window glass. Its use requires 
the addition of carbon as a reducing agent and is attended 
with many difficulties not met with when the carbonate is used. 
The amount of carbon added is much less than that called for 
by theory and it is impossible to give an exact explanation of 
the reaction. Sodium nitrate (Chile saltpeter), either as it 
comes from Chile (95 per cent) or refined for the better ware, 
is used as an oxidizing material to destroy organic matter and 
to change the iron to the ferric condition. Potassium carbonate 
(pearl ash, salts of tartar), usually hydrated, containing from 80 
to 85 per cent potassium carbonate, is the chief source of potas- 
sium in the glass industry, sulphates and chlorides being the 
chief impurities, In some European factories crude pearl ash 
from the sugar refineries is used in the cheaper kinds cf glass. 
Potassium nitrate is also used as an oxidizing material. 

Alkali Earths. Calcium is introduced as a carbonate, 
oxide or hydrated oxide. Limestone occurs in nature of suf- 
ficient purity for use after simply grinding. Burnt lime is also 
used, but more frequently the hydrated oxide. The advantage 
of the different forms of lime is an open question, some works 
preferring one, some another. The advantage of burnt lime 
is the saving in heat by the removal of the carbon dioxide before 
entering the furnace, while on the other hand the liberation 
of carbon dioxide from the carbonate helps stir the glass during 
the melting process. Iron in all glass-making materials is harm- 
ful, while magnesia makes the glass hard and more difficult 
to " plain/' though many American factories use a lime high in 
magnesia content without any apparent disadvantage. Barium 
is sometimes used in the form of sulphate together with carbon, 
bat more generally as a carbonate either natural or prepared. 
It produces a glass high in refractive power and is used for 
many optical purposes. 

Heavy Metals and Acid Radicles. Lead is used generally 
as red oxide or litharge to impart brilliancy and to produce 



196 ELEMENTS OF INDUSTRIAL CHEMISTRY 

glass of high refractive power. Red lead, because of the oxygen 
which it liberates, is preferred to litharge. Freedom from metallic 
lead and discoloring metallic impurities, such as copper and 
iron, is required. Zinc is used as oxide to replace lime or lead, 
especially in the modern heat-resisting glasses. It is also largely 
used in opal glass. Boric acid and borax are used in optical 
and heat-resisting glass as well as in colored glasses. Phosphate 
of lime, bone ash, is used to produce opalescence or opacity, 
depending upon the quantity. Bone ash, unless it is present 
in large quantity, requires " reheating " to bring out the opal- 
escence. Feldspar is used as a source of alkalies and alumina. 
Used with fluorspar it produces opal glass. Fluorspar used 
with feldspar or alumina produces opal glass. Iron and metallic 
sulphides (lead and zinc) are the chief harmful impurities. Cry- 
olite, sodium aluminium fluoride, used alone, produces dense 
opaque glass, but owing to its solvent action on the clay pots 
other materials are taking its place. It is largely used in making 
opal glass by the tank method. Arsenic as white oxide is used 
in opalescent and opal glass and in enamels. Tin oxide is used 
to a limited extent in colored glasses and in enamels. Antimony 
as oxide, sulphide, or metal is used in colored glasses and the 
sulphide is emoloyed in tank glass to " improve the color." 

Coloring Materials. Uranium, usually as sodium uranate, 
is used to produce a peculiar yellow fluorescent glass. When 
in the ferrous state, iron colors glass green, and yellow when 
in the ferric condition. The temperature of the furnace, how- 
ever, materially affects the state of oxidation of the iron, a high 
temperature changing it from yellow to green. As a colorant 
it is usually added as red oxide or iron scales. Chromium 
produces green and greenish-yellow glass. The oxide Cr203 
is very hard to dissolve; hence potassium dichromate or 
other metallic chromates are used. Manganese. Black oxide, 
Mn02, is the most used of all the coloring oxides. In large quan- 
tities it produces black, and in less amount purple to light pink 
color. It is used to correct the color effect of iron, which is 
always more or less present in glass material. It acts as an 
oxidizing agent also. The quantity of manganese to be used 
depends on the amount of iron present and the temperature of 
the furnace, as the hotter the furnace the more manganese is 
required. The heat " burns out the color." Nickel, as oxide, 
is used in a very limited way. European practice substitutes 
it for manganese in some glasses, but American factories 



CERAMIC MATERIALS AND PRODUCTS 197 

have not found this satisfactory. Cobalt, as oxide or smalt, 
is employed in giving an intense blue color. The blue from 
cobalt shows purple by transmitted light. Gold as chloride 
or purple of Cassius is used to produce a ruby color. Copper 
in the cuprous form produces red, in the cupric it produces a 
peacock-blue color. Selenium is used to produce a red color. 
Cadmium sulphide forms a lemon yellow color in lead-free glass. 
Both cadmium and selenium are usually added after the glass 
has been melted in the pot. Carbon is used as a reducing agent 
in sulphate glass. In the form of coke, oats, bark, and other 
organic matter it produces an amber color in lime glass. 

Pot Furnaces. The glass mixture is melted in clay cru- 
cibles or pots known as pot furnaces. These furnaces are either 
open or closed, and may be fired either direct, regenerative or 
recuperative. The direct-fired coal furnace is still used, but the 
regenerative furnace is the most satisfactory and economical of 
pot furnaces. In this type the burnt gases from the furnace are 
made to pass through firebrick checker-work flues which then 
become highly heated. The direction of the draft is then reversed 
by suitable dampers, and the incoming air and gas are led through 
while the burnt furnace gases go to heat another checker work 
which has become cooled by the incoming air and gas of the 
previous run. Thus the burnt furnace gases give up then waste 
heat to the checker work, which in turn gives it up to the incom- 
ing gas and air. In practice this reversal of draft is made every 
twenty or thirty minutes. In the recuperative furnace there 
is no reversal of draft, but the hot burnt gases pass through clay 
tubes which by conduction give up their heat to the incoming 
air and gas. This furnace is used abroad, but has not been 
adopted widely in America. 

Tank Furnace. The introduction of the tank furnace 
marked an epoch in the glass industry. The batch is put in a 
shallow fireclay tank covered with a refractory arch of silica 
brick and heat applied to the surface of the batch. The simplest 
form is intermittent or " day tank." The batch is shoveled in, the 
work holes are closed and heat is applied, either oil or gas being 
used. When the glass is " plain " the heat is reduced, the work 
holes opened, and when cooled sufficiently the glass is worked. 
These tanks are filled in the afternoon and are ready to work 
the following morning, hence the name. To obviate the loss of 
heat by this method continuous tanks are used. These are 
usually much larger than the day tanks and are usually divided 



198 ELEMENTS OF INDUSTRIAL CHEMISTRY 

into compartments by fireclay obstructions. The batch is filled 
in at one end of the tank, and after melting flows under the 
obstruction to the working end. As fast as the glass is worked 
out, a new batch is introduced so that the melting and working 
go on continuously, thus maintaining a nearly constant level of 
glass. The continuous tank is the most economical form of glass 
furnace, and wherever large quantities of glass are made, it is 
used. The glass produced is not so good in color as that made 
in closed pots, so that for the finest ware or where small quan- 
tities are made, pot furnaces are still employed. 

Pots vary in size from those holding but a few pounds (known 
as monkeys) to those holding several tons. The life of a pot 
varies greatly. It may be broken from the outside by a sudden 
change of temperature, or by one of the many other causes, but 
the natural end of a pot is by corrosion from the inside. This 
corrosion varies with the different kind of batches. Some pots 
may last but a few weeks, while others may remain perfectly 
good for a year. Sometimes a pot is taken out before it breaks 
because it is introducing small pieces of clay (stones) into the 
glass. 

Melting Process. The batch, made by weighing and 
carefully mixing the various materials together with some broken 
glass (cullet), is filled into the pot and the stoppers luted on. 
After this charge has melted more material is added until the 
pot is full; usually one such " topping " is sufficient to do this, 
but sometimes it must be repeated. 

Casting. Plate glass is made in open pots that can be 
removed from the furnace and their contents poured on a casting 
table and then rolled to the desired thickness by a metal roller. 
The plate of cast glass is then transferred to a kiln or annealing 
oven (lehr) and gradually allowed to cool. After the plate, which 
is rough and uneven, is cooled, it is fastened to a table with plaster 
of Paris, ground with revolving iron rubbers and sand, first 
coarse, then finer until the surface is even and smooth. It is then 
polished by felt-covered rubbers and rouge paste. The plate is 
then reversed and the other side ground and polished. 

Unpolished plate glass, known as rough plate is made simi- 
larly to regular plate glass excepting that the glass is taken from 
the pot in large steel ladles and poured on a table between guides. 
The table or the roller often have a design on them, thus pro- 
ducing ornamental effects in the glass. 

Wire glass is rolled plate in which wire has been imbedded 



CERAMIC MATERIALS AND PRODUCTS 199 

during the rolling process. Special care is necessary to prevent 
this glass from flying apart, owing to unequal expansion of the 
glass and wire. Polished plate glass of opal and black glass 
have been made and used for table tops, sanitary wall, and for 
other purposes. 

Pressing. Glass is gathered on the end of an iron rod 
(punty) by revolving it rapidly in the molten glass. It is then 
carried to the workman (presser), who cuts off with shears the 
amount desired and allows it to drop into the mold. A metal 
plunger is then forced into the mold and forces the glass to fill 
the space between the plunger and the mold. When the glass 
has become firm, the plunger is withdrawn, the mold opened 
and the article either sent direct to the annealing oven or first 
reheated in an auxiliary furnace (glory hole) to remove mold 
marks or to alter the shape. 

Press molds are made of cast iron and so constructed that 
the pressed article can be easily removed. The temperature of 
the mold and plunger is regulated by streams of air blown against 
them, the expansion and contraction of the mold being carefully 
controlled by the workman. The plunger is usually operated 
by hand power, but for some purpose steam or compressed air 
is used. 

Blowing. Window glass until recently was entirely hand 
made, but machines are being introduced which are replacing 
hand labor. In the hand-made glass the workman gathers a lump 
of glass on the end of a hollow iron pipe and after cooling it a 
little, introduces it into the molten glass and gathers more. This 
is repeated until he has sufficient for his purpose. Then by blow- 
ing and swinging and further manipulation, he produces a large 
cylinder of glass. The surplus glass is cracked off the ends of 
the cylinder and it is cracked lengthwise for the next operation. 
The cylinder is then gradually heated in a flattened oven and as 
it begins to soften it is flattened by rubbing on a flat stone, after 
which it is transferred to the annealing oven and gradually with- 
drawn from the heat. 

Window glass is now generally made in continuous tanks, 
which have replaced the old open-pot furnaces. 

Machine-made window glass is made by immersing a blow- 
pipe in molten glass, introducing compressed air and gradually 
withdrawing the blowpipe from the molten glass. By carefully 
regulating the speed of withdrawal and the amount of air intro- 
duced cylinders of any length are made and flattened as usual. 



200 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Crown Glass. Crown glass, once the chief source of sheet 
glass, is now made only for special purposes, such as microscope 
slides and cover-glasses, where a surface free from imperfections 
is required. It is made by blowing a ball of glass, attaching to 
the side away from the gathering iron a hot iron rod (punty) 
and cracking it off the gathering iron. The glass is then heated 
and rapidly revolved until it forms a large flat disk, when it is 
annealed and selected. 

Hollow Ware. Hollow ware is shaped in molds of metal 
or wood. The glass is gathered on a hollow pipe, and after 
shaping by rolling on a polished plate (marver) or revolving in 
a hollow iron or wooden block it is blown into the mold and takes 
its shape. 

In the case of chimneys, tumblers and other cylindrical 
articles the glass is revolved in the mold and shows no joint or 
mold mark. Such molds are lined with charcoal or special 
paste which enables the glass to be turned. In the case of lan- 
tern globes or articles with raised or sunken patterns the glass 
is blown without turning and takes the exact impression of the 
mold (iron mold). 

Bottles. Bottles are made by blowing in a mold, and 
after reheating the neck is finished with a special tool. 

Optical Glass. Optical glass is usually made in a one-pot 
furnace and differs from other glass in being allowed to remain in 
the pot until it has become cool. The batch is melted and after 
it has become " plain " is stirred with a burnt fireclay rod to 
produce uniformity and destroy striae. Then the glass is quickly 
cooled until it loses its fluidity, and after this it is very gradually 
cooled. When cool the pot is broken open and the glass sorted. 
Only a small portion is fit for use. In recent times advances have 
been made in this kind of glass, especially at Jena, where many 
of the optical glasses have originated. 

Colored Glass. Amber is produced by the addition of 
carbonaceous matter, e.g.-, grain, coke, coal, sawdust, or other 
organic matter, to a lime glass. The intensity and shade of color 
depend on the kind and quantity of matter added. Amber is 
also produced by sulphur and certain sulphides. Black is pro- 
duced by an excess of coloring matter such as manganese, cobalt, 
or iron. Blue can be produced by cobalt or copper. When 
produced by cobalt it is dark, showing purple by transmitted 
light. The copper blue is a less intense color, bordering on the 
green. Canary, a special color produced by uranium. Green, 



CERAMIC MATERIALS AND PRODUCTS 201 

Chromium or iron alone will produce a green glass, though 
it is usually made by combining several oxides, such as cop- 
per and iron or chromium and copper. Gray, H London 
smoke." When substances producing complementary colors are 
added to the same glass a gray color is produced. Opalescent. 
Glass resembling the opal is produced by the addition of arsenious 
oxide and calcium phosphate. When this glass comes from the 
pot it is colorless, but on allowing it to cool and then reheating, 
the opalescence is developed. If the cooling is carried too far 
the opalescence is lost and a milky effect produced. Opal or 
white opaque glass was originally produced by the addition of 
cryolite or an excess of calcium phosphate (bone ash). Mix- 
tures of fluorspar and minerals containing aluminium, such as 
feldspar, have been substituted and recently artificial compounds 
bearing fluorine, such as aluminium fluoride, and sodium silico 
fluoride, have been used. Purple is produced by manganese 
dioxide. Red or Ruby is produced by gold, selenium or copper. 
In the use of copper great care is required to have the copper in 
the right condition of division and reduction. The glass, as it 
comes from the pot, is usually light green in color but on cooling 
and reheating an intense red (such as is used for railroad signal 
lights), is produced. The color, however, is usually too intense 
for use alone so it is " flashed " by gathering a small quantity 
of the ruby glass and then covering it with sufficient clear glass 
to make the desired color. " Flashing " is frequently resorted 
to in making colored sheet glass. Gold ruby is worked very 
much the same as copper ruby, excepting that it can be produced 
sufficiently light in color to be used alone, though flashing is often 
used to reduce the intensity. Gold ruby as it comes from the 
pit is colorless or yellow, but when properly cooled and reheated 
develops the ruby color. 

Decorated and Cut Glass. Decorated or painted glass 
is produced by painting on the glass with easily fusible glazes. 
These glazes are finely ground, mixed with oil and applied to the 
object and after drying it is put in a kiln and heated sufficiently 
to fuse the glazes. Cut glass is usually a highly refractive lead 
glass which when cut shows a beautiful play of prismatic color. 
The design is first marked out with red paint and then " roughed " 
with sand on an iron wheel. It is then " smoothed "ona fine- 
grained stone wheel and finally polished on a wood wheel with 
putty and pumice. Of recent years this last operation has been 
replaced by dipping in strong hydrofluoric acid. Glass is obscured 



202 ELEMENTS OF INDUSTRIAL CHEMISTRY 

or roughed by means of sand blast or by dipping in a bath of 
alkaline fluorides. 

In etching designs on glass a print is made on paper, using a 
protective wax as ink. This print is transferred by rubbing it 
upon the glass. The paper is removed, leaving the ink design 
on the glass. The inside of the article is now protected by wax 
and then immersed in hydrofluoric acid. The acid etches the 
part exposed, but does not affect the parts protected by the ink 
or - wax. The wax is then removed by hot water, leaving the 
finished design. Often the glass is first obscured by the sand 
blast and the design etched in the roughened surface. 

Annealing. In all the processes of manufactuer, with 
bat a few exceptions, the finished articles while still hot are taken 
to an oven and gradually cooled. If glass is cooled suddenly it 
develops great internal strain so that it is likely to fall, to pieces 
under change of temperature or when its surface is scratched. 

To obtain glass free from strain it must be " annealed " or 
cooled gradually. This is accomplished either by placing the 
finished article in a heated room and allowing the fire gradually 
to die out (kilns or ovens) or by gradually withdrawing the article 
from the heat (lehrs). The former method is used for heavy 
articles such as carboys, plate glass, blanks for cutting, and 
optical glass, while the continuous lehr is used for lighter ware. 
Recently, however, such improvements have been made in con- 
tinuous lehrs that large articles and even plate glass can be 
successfully annealed in them. 

The time of annealing varies from a few hours in the lehrs 
to a week or more in the kilns, depending on the thickness and 
composition of the glass. In annealing optical glass the cooling 
is carefully controlled and of long duration, as any sign of internal 
strain renders it unfit for use. 



CHAPTER VIII 
PIGMENTS 

DEFINITION. Pigments are mineral or organic bodies used 
to give body or impart color to a base by admixture with its 
substance. They are usually insoluble in water, oils or other 
neutral liquids. It is desirable that the pigments be opaque in 
order to give good " covering power," or that they possess a high 
tinting value. The color of a pigment depends upon the amount 
and kind of light that it reflects and should entirely conceal the 
surface to which it is applied. Some pigments have sufficient 
body to be used alone, while others can be employed only in conr- 
bination. In order to apply these pigments they must be mixed 
with some form of vehicle that binds them to the surface upon 
which they are placed. A pigment or mixture of pigments so 
bound to a surface may be applied for protective or decorative 
purposes or may serve as both. 

APPLICATION. Protective paint, by which is meant paint 
used for the purpose of protecting the surface to which it is ap- 
plied, is relatively new. In Europe building construction was 
of such a character, and is largely so to-day, that paint is not 
used to any great extent on the exterior of dwellings. Only in a 
pioneer country like America where domiciles were made of wood, 
was it found necessary to apply an exterior coating to preserve 
the wood. 

For decorative and preservative effect, we find more evidence 
of the early use of paint in England than we do in any other 
country. There are items of expense in the reign of Edward I 
showing the use of paint as early as the year 1274. 

Up to the latter part of the fourteenth century, however, oil 
painting for artistic purposes was not an exact art. To Hubert 
and Jan Van Eyck, two Dutchmen, belongs the credit of first 
having made public their manner of oil painting by means of 
pigment ground as near as we know in linseed oil. 

Occasionally we hear a complaint that the pigments made 
nowadays are not as good as those that were made in former 

203 



204 ELEMENTS OF INDUSTRIAL CHEMISTRY 

years, and the poverty of oar pigments is the cause of the early 
decay of many of our paintings. 

An error of this kind deserves correction, for the art of manu- 
facture of colors has never reached a higher plane than it has at 
present, but to the ignorance of the painters and to the greed 
of paint-makers must we attribute the fugitiveness of our paint- 
ings. As nearly as can be determined there existed between the 
twelfth and the seventeenth centuries, at most nine or ten pig- 
ments. To-day we have 215 or more, 200 of which ought never 
to be used for permanent artistic painting. 

When we see a painter with a pot of paint and brush paint- 
ing either a steel or wooden structure, we imagine without further 
thought that that is the use to which most paints are put. As 
a matter of fact, paints and colors are used in enormous quan- 
tities in the arts and sciences for other than decorative or pro- 
tective purposes. The following is a list of the purchases of the 
Bureau of Engraving and Printing, Washington, D. C. for the year 
1910, showing the actual contract for 1,599,900 lbs. of pigments: 

Lbs. 

White 802,200 

Black 297,500 

Blue 52,000 

Green 180,000 

Red 68,200 

Yellow 200,000 

1,599,900 

These pigments are identical in every respect with those used 
for general painting, and yet all these pigments are used for the 
purpose of printing the currency and the postage stamps of this 
Government. 

The printing ink industry in the United States consumes 
enormous amounts of paint. In some instances the paint is 
ground in a varnish made of linseed oil, but for book and news- 
paper ink linseed oil is not used, but resinous mediums which act 
as a binding material for the pigment. 

The floor oil cloth and table oil cloth industries are also 
enormous users of paint in the strict sense of the word; and while 
it is true that the mixtures which they make differ from the 
house painters' mixtures, the principle involved is identically the 
same as that of ordinary paint. 



PIGMENTS 



205 



The shoe and leather industries are users of paint materials 
in large quantities, for making patent and harness leather, and so 
is the wall-paper industry, the window-shade industry, the rubber 
industry, and the cement industry, all using for their color effects 
the same pigments that are used for ordinary painting. 

In the strict sense of the word, paint which is used on con- 
crete, steel or wood, is an engineering material, and serves a pur- 
pose which is far more valuable than we imagine. 

The pigments used in ordinary general manufacture of paints 
are as follows: 



Whites 

White lead 

Sublimed white lead 

Zinc oxide 

Lithophone 

Barytes 

Whiting 

Gypsum 

China clay 

Asbestine 

Silica 

Zinc white lead 

Satin white 

Yellows 

Chrome yellow 
Yellow ochre 
Cadmium yellow 
Oroiment 
Litharge 
Gamboge 
Indian yellow 



Blues 
Ultramarine 
Prussian blue 
Smalt 

Cobalt blue 
Copper blue 
Chinese blue 

Violets 

Ultramarine 



Reds 

Red lead 
Chrome red 
Red ochre 
Venetian red 
Vermilion 
Realgar 
Antimony red 
Carmine 



Greens 
Ultramarine 
Brunswick green 
Chrome green 
Guignet's green 
Copper green 
Arsenic green 

Blacks 
Lamp black 
Drop black 
Graphite 
Ivory black 

Oranges 
Orange mineral 
Chrome orange 
Antimony orange 

Browns 
Lnibers 

Vandyke brown 
Sepia 



Many other pigments, both natural and artificial, are in use, 
but are not used to such an extent as the list given above. A 
large class of bodies known as " Lakes " are also used extensively 
and will be taken up in order in this chapter. 

WHITE LEAD. The name white lead applies to a compound 
consisting of carbonate of lead and hydrate of lead in chemical 
union. It is a commercial name, and is distinctive of a definite 
product which has been upon the market for hundreds of years. 



206 ELEMENTS OF INDUSTRIAL CHEMISTRY 

For the manufacture of white lead a very pure pig lead is 
usually needed, especially in such processes as do not result in the 
removal of some of the impurities at some point in the manu- 
facturing process. 

There is probably no chemical product in so general use for 
which more patents have been taken out claiming to revolutionize 
processes of manufacture. Some of these have been tried on a 
commercial scale and some have not passed beyond the issuance 
of patents. Most have been ineffective. 

To-day in the United States there are four processes in prac- 
tical commercial operation. These are the Dutch, the Carter, 
the Matheson and the Rowley or Mild process. There is also 
said to be an electrolytic process in operation in Boston, but 
practically no information is obtainable regarding it. All of these 
processes except the Mild process use acetate of lead as an assist- 
ing agent in the process. The great bulk of white lead in the 
United States is manufactured by the Dutch process. Next in 
volume of product is the Carter process. 

The Dutch Process 

Corroding. To change pig lead into white lead, it is subjected 
to the corroding gases produced by the fermentation of refuse 
tan bark. Special buildings are provided for this purpose, known 
as " corroding houses." These " corroding houses " are build- 
ings about 30 ft. high with floor-space frequently about 20X40 
ft. The floor of this building may be of ordinary earth, and 
upon it a layer of spent tan bark is placed about 20 ins. thick. 
On this is placed a layer of corroding pots, Fig. 71, covering the 
entire floor, except around the edges, where tan bark, known as 
" banking," is packed. 

In each corroding pot about half a pint of weak acetic acid, 
containing about 2 \ per cent of glacial acetic acid, is placed. 
These pots are then filled with lead buckles. On top of the 
pots a layer of boards is placed, and on these boards another 
layer of tan bark. Another layer of pots is placed on this second 
layer of tan bark; these pots are filled, as with the first layer, 
and other layers are placed on this until there are from eight 
to ten layers or " tiers " in the stack. 

For the corrosion of lead to white lead, a certain amount of 
ventilation is necessary so that the moisture can be carried off 
from the stack. This is done in various ways. A typical way 



PIGMENTS 



207 



is to provide a wooden pipe that shall run from each tier up 
near the center of the stack to the top. On the top of this pipe 
is an outlet which may be opened or closed as may be desired. 

Chemical Change. When the stack has been built, the tan 
bark commences to ferment, liberating carbon dioxide, and 
generating considerable heat. The heat causes the acetic acid 
to evaporate and its fumes attack the lead buckles. In a short 




Fig. 71. 

time these buckles are covered with a layer of basic acetate of 
lead. The carbon dioxide generated by the fermentation of 
the tan bark then decomposes the basic acetate of lead, pro- 
ducing white lead or basic carbonate and liberating neutral acetate 
of lead, which has a strong solvent action upon lead itself. This 
fermentation and corrosion of the lead continues until most of 
the lead is changed into white lead. At times the heat gen- 
erated by the fermentation of the tan bark rises rather high, 
sometimes exceeding 180° F. 

Grinding. When the fermentation of the tan bark has 



208 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



practically ceased and the corroding action is nearly finished, 
the " stack," as the whole body of tiers is called, is taken down 
or " stripped," Fig. 72, commencing at the top. The corroding 
operation takes from 100 to 130 days. When the stack is stripped, 
it is found that the metallic lead that was originally in the pots 
has been changed to a white, porcelain-like material, which is 
white lead. All of the metallic lead originally present has not 
been corroded, however. It is necessary, therefore, to remove 
the remaining metallic lead, and to grind the white lead finely 




Fig. 72. 

in order to make it a suitable paint material. This work is 
done largely in iron machinery that is air-tight, so that the 
dust formed will not escape. The corroded lead from the stacks 
is first passed through a screen, covered with sheet-steel perfo- 
rated with rather large holes. This screen tumbles the lead about, 
breaking up the white lead sufficiently, so that it passes through 
the holes in the steel covering, while the large pieces of metallic 
lead pass out as tailings, to be remelted for further use. This 
coarse white lead is then passed through rolls and fine screens 
to remove the finer metallic lead; following which, the white 
lead reaches the condition known as " unground carbonate " 



PIGMENTS 209 

and becomes suitable for water-grinding. The unground car- 
bonate is mixed with water and ground with high-speed mill- 
stones, so that every particle will pass through fine silk bolting 
cloth. The white lead in water after grinding is also floated 
a long distance so that any coarse and unground particles may 
settle out. The water containing the white lead is pumped into 
large tanks and allowed to settle. 

Pulp Lead. The thick mixture of white lead and water, 
called " pulp," which settles to the bottom, is pumped onto 
drying pans made of copper and dried with exhaust steam, 
the product being the dry lead of v commerce. This dry white 
lead is mixed with linseed-oil and ground through burr mills 
to produce a white lead paste, which is the commercial white 
lead in oil. Sometimes, the white lead pulp is mixed directly 
with refined linseed-oil in special mixers, the oil combining 
mechanically with the white lead, producing white lead in oil 
of commerce, the water being eliminated. 

The Carter Process 

Chemically, white lead manufactured by the Carter process 
is the same as when manufactured by the Old Dutch process. 
In each case pure metallic lead is converted into basic lead 
acetates, which are acted upon by carbon dioxide to form basic 
carbonate of lead, or white lead. 

The Carter process starts with pig lead, a grade commercially 
known as " corroding," which is as free as possible from bis- 
muth, antimony, and other impurities. 

The first step is to atomize the metallic lead, the method 
being substantially the same as atomizing a liquid in the ordinary 
nasal atomizer. The pig lead is melted in a kettle to which is 
affixed a nozzle through which the molten lead flows by gravity. 
At the outlet it is struck by a jet of superheated steam which 
atomizes or blows the lead into very fine particles which are 
very slightly oxidized. 

In some text-books on paints and paint pigments, the Carter 
process is referred to as " the quick process." This is a little 
misleading, for while the time of corrosion is cut down from 
about 120 days by the Dutch process to about fifteen days, the 
mass of metallic lead exposed to the corroding agencies is re- 
duced in much greater proportion. 

The powdered lead, in charges of about 4000 lbs. is then 



210 



ELEMENTS OF INDUSTRIAL CHEMISTRY 




Fig. 73. 



placed in wooden cylinders, Fig. 73, about 6 ft. in diameter and 
10 ft. long, which revolve very slowly on their own horizontal 
axes. 

The metallic lead in the cylinders is treated with dilute 
acetic acid (vinegar) and carbon dioxide (carbonic acid gas). 

A very weak solution of the acetic 
acid is sprayed into the cylinders 
at intervals. The carbon dioxide 
is admitted through the center of 
the head and is produced by the 
perfect combustion, in the presence 
of an excess of oxygen, of carefully 
selected coke. The coke is burned 
under boilers so as to utilize its 
calorific value. The lead in the 
cylinders is kept moist with water 
during corrosion and a certain per 
cent of oxygen (air) passes into the cylinders with the carbon 
dioxide. 

The action of the acetic acid upon an excess of metallic 
lead and lead oxide produces various basic lead acetates. The 
carbon dioxide acting on these basic acetates forms basic lead 
carbonate or white lead. The acetic acid, freed by the action 
of the carbon dioxide on the basic acetates, acts again on the 
excess of metallic lead and lead oxide and is again liberated, and 
so on in cycles until corrosion is complete. 

As the cylinders slowly revolve, the pulverized lead is car- 
ried upward on the interior of the cylinder and rolls down to 
the bottom, exposing new particles to the corroding agencies. 
The heavy mass also performs most efficiently the functions of a 
tube mill in grinding the carbonate off the metallic particles 
as fast as it is formed and reducing it to an exceedingly fine 
powder. 

By the Carter process corrosion is complete in about fifteen 
days. No artificial heat' is required, sufficient heat being gen- 
erated by the chemical combination to keep the contents of the 
cylinder at about 145° F. during corrosion. 

At the proper stage, the cylinders are emptied and the white 
lead is then washed and agitated in water, removing any traces 
of acetic acid or acetate of lead. It is then floated in water to 
remove the small particles of coarse lead, if any, and is then 
pumped into storage tubs, where the lead settles in the form of 



PIGMENTS 211 

a heavy pulp. After evaporating the water from the pulp, 
commercial dry white lead results. 

For general use, white lead is put up in stiff paste form to 
facilitate mixing into paint. This paste consists of 92 per cent 
of hydrated carbonate of lead and 8 per cent of pure raw linseed oil. 
This paste is produced in two ways: one by chasing, mixing and 
grinding in a double set of heavy buhr-stone mills,* dry white 
lead and pure linseed oil; the other by mixing the lead pulp 
(lead and water) with linseed oil in what is known as pulp 
machines, the white lead taking up the oil to the exclusion of 
the water and becoming " lead in oil," which is then chased 
and mixed and run through the heavy buhr-stone mills. The 
pulp process simply does away with drying the lead pulp, and 
the only purpose of the heavy grinding is to secure complete 
incorporation of the lead and the oil. Properly ground lead 
in oil, ground either dry or from pulp, does not contain more than 
0.5 per cent of free moisture. 

The last step in the Carter process is to convey the paste white 
lead from the mills to storage tanks, each of 75 tons capacity, 
there it is allowed to stand for several days before it is drawn 
off and filled into kegs. The pressure of the lead in these tanks 
completes a perfect saturation of the lead with the oil and forms 
a very smooth, unctuous paste. 

The Matheson Process 

This process is a development of the process usually attached 
to the name of Thenard, who introduced it at Clichy, France. 
It involves the use of a solution of basic acetate of lead into which 
carbonic acid more or less purified is conducted. The carbonic 
acid combines with the basic lead, removing it from its combina- 
tion with the acetate of lead, the carbonate compound separating 
as a precipitate of white lead. The white lead thus produced 
is removed by filtration, washed with water and dried. The 
nearly neutral lead acetate is then recharged with lead oxide to 
bring it to the proper basicity and the operation repeated. The 
lead acetate acts therefore as a carrier for the lead and theoretic- 
ally should all be recovered. A small amount of the acetate of 
lead remains with the white lead, however, probably as a hexabasic 
acetate. 



212 ELEMENTS OF INDUSTRIAL CHEMISTRY 



The Rowley or Mild Process 

This process, although similar to, differs from, the Carter proc- 
ess in that no acetic acid is used. It had long been assumed 
that white lead could not be made without a carrier like acetate 
of lead. The advent of this process shows that this assumption 
was erroneous. The lead is atomized in a manner similar to that 
used in the Carter process. The atomized lead after proper 
notation is run into oxidizers which consist of mechanically 
agitated tanks containing water into which air under low pressure 
is forced. The oxide of lead so produced — which may be more or 
less in the form of hydroxide — is floated away from the unoxidized 
metal and run into carbonators which are horizontal rotating 
cylinders where, under the action of carbonic acid gas (contained 
in purified flue gas), white lead is produced. It is then allowed to 
settle and the thickened pulp is pumped onto drying pans and dried. 

SUBLIMED WHITE LEAD. Sublimed white lead is an amor- 
phous white pigment possessing excellent covering and hiding 
power, and is very uniform and fine in grain. It is a direct 
furnace product obtained by the sublimation of galena, and within 
the last ten years it has come into great prominence among 
paint makers, it now being regarded as a stable, uniform, and very 
valuable paint pigment. The author has examined a great 
many paints containing sublimed lead. Among one hundred 
reputable paint manufacturers in the United States sixty-five 
used sublimed lead. About eight thousand tons were used in the 
United States in 1905. Considering the fact that sublimed lead 
as a pigment is about twenty-five years old, it is very likely, 
judging from its qualities, that it will be used more universally 
and in larger quantities in the future. 

When mixed with other pigments, such as zinc oxide, car- 
bonate of lead, and the proper reducing materials added, such as 
silica, clay, barium sulphate, etc., it produces a most excellent 
paint, and at the seashore its wearing quality is superior to that 
of carbonate of lead. In composition it is fairly uniform. From 
the analysis of thirty-four samples of sublimed lead its composi- 
tion may be quoted as 75 per cent lead sulphate, 20 per cent 
lead oxide, and 5 per cent zinc oxide, although each of these 
figures will vary slightly either way. Corroded white lead also 
varies in its percentage of hydrate, but for analytical purposes 
a constant must be admitted which will fairly represent the 
composition. 



PIGMENTS 213 

The question has arisen of late years whether sublimed lead 
is a mixture of the three components just cited, or whether it is 
a combination of lead sulphate and lead oxide with the mechan- 
ical addition of zinc oxide. Inasmuch as all the lead oxides that 
are known in commerce or in chemistry are yellow, red, or brown, 
it is held by many that the lead oxide of sublimed lead is really an 
oxysulphate, or, in other words, a basic sulphate of lead. A mix- 
ture of precipitated lead sulphate, litharge, and zinc white in 
approximately the proportions found in sublimed lead, when 
ground in oil and reduced to the proper consistency, dries totally 
differently from sublimed white lead ; in fact, sublimed lead when 
ground in raw linseed oil takes two days to dry dust free, but the 
mixture just cited will dry sufficiently hard for repainting in twelve 
hours, because lead sulphate is a fair drier and lead oxide a power- 
ful one. Yet the oxysulphate, having the same composition, 
behaves totally differently from the mixture and in addition is of 
a different color. 

Under the microscope, sublimed lead shows the absence of 
crystals and remarkable uniformity of grain. Being a much 
more complete chemical body than the other lead paints, it does 
not react on linseed oil and therefore makes a much more durable 
paint compound. It has been urged that sublimed lead is not as 
susceptible to sulphur gases as white lead, but this the author has 
not been able to substantiate, for while it may take hydrogen sul- 
phide a longer time to discolor it, it is simply a question of degree, 
and it is acted upon by sulphur gases, although not as quickly as 
white lead. 

Sublimed lead can be determined in a white mixed paint 
without any difficulty, owing to the established ratio between 
lead oxide and lead sulphate. The percentage of free zinc 
sulphate in sublimed white lead varies from a trace to a half per 
cent, and many times a chemist will report more zinc sulphate 
than is actually present, because in washing or boiling a dry or 
extracted sample the lead sulphate may interact with the zinc 
oxide and show a larger percentage of zinc sulphate than is 
really present in the dry products before analysis. 

Sublimed white lead as a marine or ship paint is of much 
value, owing to its hardness of drying and imperviousness of film. 

ZINC OXIDE. As a paint pigment zinc oxide is but little 
over fifty years old. Its discovery was made by Le Claire in 
France and by Samuel T. Jones in America at about the same 
time. The product made by the Le Claire process is known as 



214 ELEMENTS OF INDUSTRIAL CHEMISTRY 

" French process " or " French zinc oxide," while that made 
by the Jones process is known as " American process " or 
as " American process zinc oxide." 

French Process. The raw material for this process is metallic 
zinc, which is obtained from its ores as " spelter " by reduction, 
distillation and condensation. The vaporized zinc as it comes 
in contact with the air at high temperatures takes fire, thus pro- 
ducing a smoke which is conducted into large chambers where 
it settles and from whence it is removed from time to time for 
shipment. Much zinc oxide is made in this country by the French 
process and is known as " Florence zinc." It is sold in three 
grades, mmely " White Seal," " Green Seal," and " Red Seal." 

American Process. In this process the raw materials are ores 
of zinc. The ore and reducing material are heated in a special 
form of furnace so arranged that the escaping vapors are brought 
into direct contact with air. The fume is then conducted by 
means of a fan into the collecting system. The collecting system 
consists of a series of bags which are suspended vertically from 
a system of horizontal pipes. From these bags the oxide is 
removed, bolted and graded for shipment. American zinc 
oxides come on the market as " Selected," " XX Black Brand," 
" Special," and " XX Red Brand." 

Owing to the fact that zinc oxides have a great powder to carry 
oil, give a very white color and help to harden the film, they have 
met with quite general application. They are especially help- 
ful as a constituent of mixed paints. 

LlTHOPONE. When solutions of zinc sulphate and barium 
sulphide are mixed together in molecular proportions, a heavy 
flocculent precipitate is formed according to the following reac- 
tion: 

ZnS0 4 +BaS = ZnS-f-BaS0 4 . 

The theoretical percentage will be 29| per cent zinc sulphide and 
70J per cent barium sulphate. This precipitate as such has no 
body or covering power, and when washed and dried is totally 
unfit for paint purposes, but John B. Orr, of England, in 1880 
discovered that when it is heated to dull redness, suddenly 
plunged into water, ground in its pulp state, thoroughly washed 
and dried, its characteristics are totally changed, and it makes 
a very effective and durable pigment for paint purposes. In 
the first place, it is a brilliant white; in the second place, it is 
extremely fine in texture, and in the third place, it has the same 



PIGMENTS 215 

tinctorial strength but more hiding power than pure zinc oxide. 
Inasmuch as it is a complete chemical compound it is stable in 
every medium known for paint purposes, excepting those which 
are highly acid. It took several years to perfect the manufacture 
of lithopone, but it may be said that at the present time litho- 
pone is made with great uniformity and has valuable properties. 

Lithopone is likewise very largely used in the cheaper grades 
of enamel paints, because it does not combine with rosin or semi- 
fossil resin varnishes and therefore remains unaltered in the pack- 
age. As an interior white, a first-coat white, a ready-mixed flat 
paint for surface, or as a pigment in the lighter shades for floor 
paints, lithopone cannot be excelled for its body, durability, 
hardness, fineness of grain, and ease of application. It does not 
oxidize progressively, and this single feature has made it invalu- 
able to the table oilcloth and floor oilcloth industry throughout 
the world. Its indiscriminate use, however, is not to be recom- 
mended, and the paint chemist should be permitted to decide 
when its value is the greatest. As a marine paint, either as a 
first coat or for making neutral paints where other whites would 
be necessary, it is found to outlast both zinc oxide and lead car- 
bonate. 

BARYTES. This material is the sulphate of barium. It is 
a very heavy white pigment and is sometimes used as an adulter- 
ant of white lead. When employed in small amount, however, 
it gives strength to the film and should not be considered as an 
adulterant. 

WHITING. This is the carbonate of calcium and for certain 
purposes finds application in the paint manufacture. 

ASBESTINE. This material is a magnesium silicate pre- 
pared from asbestos. Its use in paint is as a binder and owing to 
its nature finds application as an emulsifier. That is, it helps 
to hold other pigments in suspension. 

Quicksilver Vermilion. Quicksilver vermilion is the 
amorphous mercury sulphide which is normally black, but when 
made with sulphur in the presence of an alkaline solution, it be- 
comes bright red. 

Red Lead and Orange Mineral. Red lead and orange 
mineral are the red oxides of lead and are both chemically alike. 
Red lead, is, however, made by heating litharge, which is the 
ground oxide of lead, and orange mineral is made by heating white 
lead until all the water and carbonic acid are driven off. 

VENETIAN Red. This is a ferric oxide containing gypsum 



216 ELEMENTS OF INDUSTRIAL CHEMISTRY 

in varying quantities, obtained by heating ferrous sulphate in 
the presence of calcium oxide. 

INDIAN RED. Indian red is generally a very pure form of 
ferric oxide made by heating copperas or ferrous sulphate until 
it is converted into ferric oxide. 

Permanent Vermilion. Permanent vermilion is usually 
orange mineral tinted with para-nitr aniline. 

Burnt Ochre and American Sienna. Burnt ochre and 
American sienna are analogous, being made of hydrated oxide of 
iron and clay ore burnt until the ferrous salt is converted into 
ferric. 

CHROME YELLOW. Chrome yellow is chromate of lead 
made by adding chromate of potassium or sodium to a basic 
lead nitrate solution. The precipitate thus formed is washed, 
pressed and dried. 

Ultramarine Blue, Cobalt Blue. Ultramarine blue and 
cobalt blue may both be made from the natural minerals. 

Ultramarine blue whether artificial or genuine is chemically 
the same, with the one difference that the genuine ultramarine 
blue is the powdered mineral known as lapis lazuli, and ordinarily 
is the blue known under that name, but the mineral itself is found 
at times in an impure state either admixed with slate or gang 
rock, or contaminated slightly with other minerals. The genu- 
ine ultramarine bhe may run, therefore, from a very deep blue 
to a very pale ashen blue; in fact, the lapis lazuli which lies 
adjacent to the gang rock is ground up and sold under the name 
of ultramarine ashes, which is nothing more nor less than a very 
weak variety of genuine ultramarine blue. 

From the standpoint of exposure to light or drying quality, 
the artificial ultramarine is just as good as the genuine, and the 
only advantage that the genuine has over the artificial is that the 
genuine is not so quickly affected by acids as the artificial is. 

PRUSSIAN BLUE. This is a very permanent and powerful 
color made by precipitating solutions of ferrous salts with ferro- 
cyanide of potassium, and subsequently converting into the 
ferric condition. 

CHROME GREEN. Chrome green is a mixture of chrome 
yellow and Prussian blue, and is not the chromium oxide described 
in the next paragraph. 

CHROMIUM OXIDE. This green is one of the most perma- 
nent greens used, but it is not extensively employed in the manu- 
facture of mixed paints except where absolute permanence is 



PIGMENTS 217 

necessary. It is met with occasionally in railway paints for 
switch target signals, and as a mixed paint to be used on vessels 
for repainting the receptacle in which the starboard lights rest. 
It is not a brilliant green and cannot be compared with the 
chrome greens, which are mixtures of chrome yellow and Prus- 
sian blue. It is more of an olive shade. 

Lamp Black and Carbon Black. Both of these are con- 
densed soots, the one made from dead oil, and the other usually 
from gas. They are pure carbon. 

GRAPHITE. Graphite is either artificial or natural, and very 
seldom contains more than 90 per cent of carbon. It has a 
peculiar silvery luster by which it can be identified. 

CHARCOAL AND COAL. Charcoal and coal are analogous 
in composition, except that charcoal black is alkaline and coal 
black acid. Vine black is also the same as charcoal black. 

MINERAL BLACK. Mineral black is usually a slate colored 
with oxide of iron. 

SILICA AND INFUSORIAL EARTH. Silica and infusorial earth 
are usually either ground quartz or the native infusorial earth 
washed and powdered. China clay and kaolin are silicates of 
alumina largely used as either reinforcing pigments or substra- 
tums for lakes. 

BARIUM SULPHATE. Barium sulphate is an artificial pre- 
cipitate, usually made from barium chloride and sodium sulphate, 
and is largely used as a lake base, and in its dry form as a rein- 
forcing pigment. The United States Navy has lately experi- 
mented with it in a very large way for making battleship gray. 

Gypsum and Terra Alba. Gypsum and terra alba are 
either artificial or natural calcium sulphate. 

Prince's Mineral and Prince's Metallic Prince's 
mineral and Prince's metallic are both oxides of iron containing 
about 40 per cent of oxide, the balance being silicate or clay. 

OCHRE. Ochre is clay stained with the hydrated oxide of iron. 

UMBER. Umber is a clay earth stained with oxides of man- 
ganese and iron. 

SIENNA. Sienna is largely composed of hydrated oxide 
of iron and a very small percentage of clay. 

Vandyke Brown. Vandyke brown is a clay earth stained 
with a bituminous compound. 

PAINT VEHICLES. The vehicles or liquids used in making 
paint are linseed oil, soya bean oil, China wood oil, fish oil, corn 
oil, turpentine, benzine, benzol, turpentine substitutes and driers. 



218 ELEMENTS OF INDUSTRIAL CHEMISTRY 

LAKES. In addition to the large number of pigments which 
are employed, we have an almost unlimited number of compounds 
which are derived from the various classes of dyestuffs. These 
compounds, known as lakes, are prepared by precipitation of the 
dyestuff with a suitable precipitant in the presence of an inert 
base, this base acting as the carrier of the color. The precipi- 
tants used depend upon the nature of the dyestuff, those ordinarily 
employed being barium chloride, calcium chloride, lead acetate, 
zinc sulphate, aluminium sulphate, and tannic acid. The base 
upon which the color is precipitated is important , as it affects the 
covering power, cheapness, and character of the pigment. These 
lakes are sold as dry colors; pulp colors, mixed with water; or 
paste colors, mixed in oil. 

These color lakes find extensive application in the manufacture 
of lithographic inks, paint colors, colors for kalsomine or wall 
finishes, and colors for wall paper and coated paper surfaces. 



CHAPTER IX 
FERTILIZERS 

FERTILIZER MATERIALS. Broadly speaking, there are two 
kinds of fertilizer materials: those which are in themselves a 
direct source of plant food, and those which, by their action, 
tend to make plant food fertilizers more available. While 
crops may grow T without the use of fertilizers of the second class, 
no crops can mature without fertilizers of the first class. 

Fertilizers of the second class comprise lime, gypsum, and 
common salt; they are all useful, but rarely indispensable. These 
are sometimes called " stimulant fertilizers." They tend to 
make rapidly available the stores of ammonia, phosphoric acid, 
and potash naturally present in the soil. When stimulant fer- 
tilizers are used exclusively for a term of years, the soil loses 
ammonh, phosphoric acid, and potash. The inevitable result of 
such treatment must be finally the exhaustion of these important 
food constituents of the soil. 

True fertilizers contain forms of plant food which contribute 
directly to the growth and substance of plants. Such materials 
may contain either ammonia, potash or phosphoric acid com- 
pounds, or all three. 

TERMS USED IN ANALYSIS. Fertilizer dealers and experi- 
ment station bulletins treat the different forms of fertilizer ma- 
terials separately, and a familiar understanding of these trade 
names is important. 

Ammonia is expressed either as nitrogen, as ammonia, or as 
nitrogen " equivalent to ammonia." There are various conditions 
in which phosphoric acid may be expressed, such as reverted, 
available, insoluble, total, and phosphoric acid " equivalent 
to bone phosphate of lime." Potash is expressed as potash, as 
potash actual, or as potash equivalent to sulphate of potassium 
or to chloride of potassium. 

All genuine commercial fertilizers owe their value to the 
kind, quality, and amount of nitrogen, phosphoric acid, and 
potash they contain. They are made by mixing more or less of 

219 



220 ELEMENTS OF INDUSTRIAL CHEMISTRY 

the several kinds of raw materials furnishing the desired ingre 
dients, and to these may be added sulphuric acid to render the 
phosphoric acid available and a filler to make up the desired 
formula. 

Expression of Formulae. One often sees formulas 
expressed in this manner, 4-8-2, or 3-6-4. It means that nitro- 
gen comes first, phosphoric acid next, and potash third, hence 
the 4-8-2 indicates a fertilizer containing 4 per cent of nitrogen, 
8 per cent of phosphoric acid, and 2 per cent potash. These 
figures multiplied by 20 give for each ton 80 lbs. nitrogen, 160 
lbs. phosphoric acid and 40 lbs. potash. 

EXPLANATIONS OF MARKET QUOTATIONS; HOW TO ESTI- 
MATE THE VALUE OF FERTILIZERS. Phosphate rock, kainit, 
bone, fish-scrap, tankage, and some other articles are commonly 
quoted and sold by the ton. The seller usually has an analysis 
of his stock, and purchasers often control this by analysis at time 
of the purchase. 

Acid phosphate is usually quoted at so much " per unit " of 
available, that is, soluble and reverted phosphoric acid. The 
meaning of the term unit is explained below. Tankage is usually 
sold with a quotation of so much " per unit of ammonia " and 
" per unit of bone phosphate." The amount of bone phosphate 
may be calculated by multiplying the amount of phosphoric 
acid by 2.1850. On the other hand, the amount of phosphoric 
acid is calculated from the bone phosphate by multiplying the 
latter by 0.4576. 

Sulphate of ammonia, nitrate of soda, and the potash salts are 
quoted and sold by the pound, and generally their wholesale and 
retail prices do not differ materially. 

Blood, azotin, and concentrated tankage are quoted at so 
much " per unit of ammonia." To reduce ammonia to nitrogen, 
multiply the per cent of ammonia by 0.8228; to make the reverse 
calculation multiply by 1.2154. A " unit of ammonia " is 1 
per cent, or 20 lbs. per ton. To illustrate: if a lot of tankage has 
7 per cent of nitrogen, equivalent to 8.50 per cent ammonia, it is 
said to contain 8 J units of ammonia, and if quoted at $2.25 per 
unit, a ton of it will cost 8| times $2.25, or $19.13. 

Tankage and fish-scrap are sometimes sold at a price, based 
on analysis, with regard to both the nitrogen and phosphoric acid 
which the product in question contains. For example : Tank- 
age, 9-20 quoted at $2.49 and 10 cents per unit, means that a 
given lot of tankage contains somewhere in the neighborhood 



FERTILIZERS 221 

of 9 per cent ammonia and 20 per cent bone phosphate, and is 

offered at $2.49 per unit of ammonia and 10 cents per unit of 

bone phosphate. A unit of ammonia, 20 lbs. is equivalent to 

(20 times 0.8228) 16.46 lbs. of nitrogen and is quoted at $2.49. 

2 49 
One pound of nitrogen, therefore, costs -~^ equal to 15.10 cents. 

A unit of bone phosphate, 20 lbs., is equivalent to 20 times 
0.4576 equal to 9.15 lbs. of phosphoric acid, and is quoted at 

10 cents. One pound of phosphoric acid therefore costs ^pp> 
equal to 1 cent. 

Hence it appears that a tankage containing 9 per cent ammonia 
and 20 per cent of bone phosphate and quoted at $2.49 and 10 
cents per unit/ costs for nitrogen 15.1 cents per pound and for 
phosphoric acid 1 cent per pound. 

The cost of such a tankage will be 9 units of ammonia at $2.49 
equal to 822.41 plus 20 units of bone phosphate at 10 cents per 
unit, or $2 or $24.41 per ton. 

Materials Furnishing Nitrogen. Guano. On the coast 
of Peru lie the Chincha Islands. These islands and the main- 
land opposite are in the dry zone of Peru in which rain seldom 
falls. They are small, high and rocky, barren and uninviting; 
yet from them has come vast wealth. Guano to the value of 
one thousand million dollars has been taken from the Chincha 
Islands. It is doubtful if there be another spot of equal size on 
the earth which has yielded so much wealth as these guano beds. 
These islands, however, are not the only source of Peruvian 
guano, as the Macabi, Guanape, the Lobos, Ballestas, and the 
Huanillos, as well as scores of small islands have also furnished 
large quantities. 

The word guano is the Spanish rendering of the Peruvian 
word huanu, meaning excrement. There are many varieties of 
Peruvian guano having different fertilizing values due to their 
different chemical constituents, but they all are alike in their 
origin. Guano is mainly the excrement of marine birds mixed 
with the remains of the birds themselves and the fish they have 
brought to land. In some cases on the Chincha Islands the 
deposits are from 160 to 180 ft. thick. The lower strata of such 
deposits may be thousands of years old. 

In reviewing this subject, L'Engrais of Paris estimates that 
in forty years over 18,500,000 tons were taken from these locali- 
ties or about 440,000 tons annually. 



222 ELEMENTS OF INDUSTRIAL CHEMISTRY 

As the penguins and pelicans are very voracious each bird 
is capable of furnishing on an average, about 32 gms. of excre- 
ment per night. It is estimated that 100 kgms. of guano, con- 
taining 14 per cent of nitrogen and 10 per cent of phosphoric 
acid, require the consumption of 600 kgms. of fish containing 2.3 
per cent nitrogen and 1.7 per cent phosphoric acid. An annual 
deposit of 40,000 tons is, therefore, the digestive product of 
3,420,000 pelicans. It is reported that while the old beds have 
been considerably reduced there are layers 30 ft. thick which 
have not been touched and which are still forming. 

The guano is taken out by shovel and pick. As the coasts are 
rough and few harbors exist, loading of steamers can be done in 
calm weather only. The water is very deep and large steamers 
can anchor close to the shore so that most of the guano can be 
loaded directly into the steamer from the shore by means of cable 
trams. In some cases, it has to be taken to the steamer in boats. 

Calcium Cyanamide. This is a product derived by heating 
calcium carbide in an atmosphere of nitrogen. The reactions 
are intricate, but may be represented by the following equation: 

CaC2+N 2 = CaCN 2 +C. 

The technical procedure is simple, but care must be taken in 
carrying out the details. The nitrogen must be technically pure 
and the complete nitrification of the carbide, necessary to pro- 
duce a high-grade product, is dependent upon progressive and 
cumulative reactions, which once started may not be checked or 
diverted at any stage except at the cost of the quality of the 
final product. 

To prepare adequately the raw cyanamide for incorporation 
into fertilizers several processes have been developed and much 
costly machinery designed, the object of such processes being 
simply to hydrate all the caustic lime and to dislodge and expel 
as a gas all the substances in the raw cyanamide which will 
produce acetylene, phosphine, and hydrogen sulphide. 

Dry Fish Scrap. The menhaden (Brevoortia tyr annus) 
belongs to the family Clupeidse and has many local names. On 
the Maine coast it is called pogy, pony fish, moss-bunker; in 
Massachusetts, hardhead bunker; in Delaware, bug fish, in addi- 
tion to those already given; on the Virginia coast, old wife, 
cheboy, ellfish, bug fish, green tail, and bughead; in North 
Carolina, fat-back and yellow-tail shad. 



FERTILIZERS 223 

When full grown the fish weigh from 10 ounces to 1J lbs. and 
measures from 12 to 15 ins. in length. They are found in 
immense schools on the American North Atlantic coast from the 
Bay of Fundy to the Mosquito Inlet, Florida. Their usual habitat 
is the bays and rivers, sometimes as far as brackish water 
extends, and ocean-ward as far as to the Gulf Stream. On the 
approach of warm weather the schools begin to appear and remain 
until cold weather sets in. Approximately a temperature of from 
60 to 70° F. appears favorable. In the Chesapeake Bay the season 
extends from March and April to November and December. The 
New Jersey fishing season begins about May 1st and ends about 
the middle of November. The habit of the fish is to congregate 
in very large schools and then swim along close to the surface of 
the water, packed closely side by side and tier on tier. As many 
as 450,000 tons of these fish have been taken in a single season. 

When a school of fish is sighted, the steamer gets as close as 
possible without scaring the fish and then lowers the two seine 
boats of whale-boat pattern. The seine is a net from 750 to 1800 
ft. long and 75 to 150 ft. deep with the usual fitting of cork and 
sinkers, and so arranged that the bottom may be drawn together, 
thus making a purse in which the fish are held. The two boats, 
each carrying an equal amount of the net, start in opposite 
directions around the school and when they have met, start 
pulling in the purse string. When the bottom is closed the 
steamer comes up and the fish are scopped from the net by means 
of large scoops worked by a derrick on the steamer. 

When a steamer has a load it returns to the factory, as the 
fish, if kept too long, soon turn soft and are then very difficult 
to handle. 

On reaching the factory, the fish are unloaded by being 
shoveled into a traveling conveyor which takes them to a belt 
which carries them into the store shed. From here they are 
carried to a continuous steam cooker, where the oil cells are 
broken and the fish bodies broken up. This requires but a few 
minutes, when the fish are run into screw presses. On leaving 
the cookers they contain about 75 per cent of water. The screw 
presses can press the fish down to about 45 to 50 per cent of 
water. Most of the oil is here liberated. 

The water and oil are run into large settling tanks and the oil 
which rises to the top is taken off. 

The fish from the presses then go to direct-heat or steam- 
heated cylindrical dryers. They are dropped into the hot end 



224 ELEMENTS OF INDUSTRIAL CHEMISTRY 

of the dryer where the flame from either soft coal or oil is pouring 
in. The water in the scrap prevents the burning of the fish as 
it immediately takes up the heat. The scrap falls to the bottom 
of the dryer and is carried around as it revolves and showered 
down through the hot gases. On reaching the end of the dryer it is 
cool enough to handle and contains about 8 per cent water. It 
is now picked up by a traveling belt and run to the storehouse 
where it is bagged ready for shipment. Great care must be 
taken in the storeroom, on account of the combustible nature of 
this material, owing to the presence of the oil left in it. It heats 
very rapidly if left in large piles and must be cooled by turning 
over. 

The capacity of a factory is usually calculated as the number 
of barrels per day of fish that it can handle. One barrel contains 
300 fish. A large and well-equipped factory will handle 700 
barrels of fish per hour, turning it out as wet acid scrap, or 
if the dryer capacity is equal to the cooking and pressing capacity 
as dry scrap. 

To produce 1 ton of dry scrap requires an average of 50 
barrels of fish, while to make 1 ton of acid scrap (wet) requires 
30 barrels of fish. In a good season about 3 gallons of oil per 
barrel of fish is recovered. 

Wet Acid Scrap. Where the plant does not have enough 
dryer capacity to take care of the catch, the excess is made into 
wet acid scrap. The fish scrap from the presses is acidulated 
with from 60 to 80 lbs. 60° Be. sulphuric acid to the ton of wet 
scrap. This converts some of the bone phosphate into the avail- 
able form and at the same time preserves the scrap from decom- 
position. Good acid scrap that has not lain long in piles will 
analyze on 50 per cent water basis as high as 7.50 to 7.75 per 
cent ammonia. 

Slaughter House Tankage. In all slaughter houses the scrap 
meat ie saved and treated for the production of " tankage." As 
all this material has more or less grease still adhering to it, it is 
first placed in large tanks and boiled under pressure till the grease, 
has left the meat and the bone. The scrap is then allowed to 
drop to the bottom of the tank and the liquor is drawn off into 
large vats. After the grease has risen to the top it is with- 
drawn. The remaining liquor is then treated for its fertilizing 
constituents as given elsewhere under " concentrated tankage." 

The scrap meat and bone, or as it is called, " tankage, " is now 
pressed to free it as much as possible from the water and ad her- 



FERTILIZERS 225 

ing grease and is then dried in rotary direct-heat or steam dryers. 
It is then ready for sale. 

In plants where the liquors are evaporated for " concentrated 
tankage " it is a general practice to mix the " stick " or thick 
liquor obtained by evaporation directly with the tankage before 
drying. This raises the percentage of ammonia and at the same 
time does away with the making of a second product. 

PHOSPHORIC ACID. This as 'used in fertilizers does not 
exist as true phosphoric acid, but as various salts of phos- 
phoric acid and lime. Soluble phosphoric acid is the mono- 
calcium phosphate formed during the process of acidulating 
phosphate rock or bone. Reverted phosphoric acid is the dieal- 
ciurn phosphate which is also formed during the process of acidu- 
lation and is soluble in neutral ammonium citrate. Available 
phosphoric acid is the sum of the soluble and reverted forms 
and is the total phosphoric acid in a condition capable of being 
absorbed by plants. 

Insoluble phosphoric acid is the tricalcium phosphate as it 
exists in phosphate rock and bone and is not available for plant 
food. Total phosphoric acid is the total amount present irrespec- 
tive of the form in which it is present. It is the sum of the above 
three forms. Phosphoric acid equivalent to bone phosphate 
simply means the total phosphoric acid calculated as the tri- 
calcium phosphate. 

Phosphatic Crude Stock. 
Furnishing insoluble phosphoric Furnishing available phosphoric 
acid: acid. 

Animal : Animal : 

Bones Dissolved bone, acid-fish- 

scrap. 
Mineral: Mineral: 

Apatite, phosphate rock Acid-phosphate from any 
from Florida, Tennessee, form of mineral phosphate, 

of blue, brown and white 
colors. 
Thomas slag. 

The Phosphate Rock Industry. From time to time 
various deoosits of phosphate rock have been found and mined 
throughout the world, but the principal workings to-day are to 
be found in Florida, South Carolina, and Tennessee in the United 



226 ELEMENTS OF INDUSTRIAL CHEMISTRY 

States, in Algeria and Gafsa in North Africa, and in Ocean and 
Christmas islands in the far east. 

The first serious attempt to obtain phosphate in this country 
was in Canada, mining what is known as Canadian apatite. 
This is a very high-grade material, but it was very expensive to 
mine and when in 1870 the South Carolina, and in 1888 the Florida 
deposits were marketed, it could not compete with them. The 
rock in South Carolina is found in two grades — river and land 
pebble. It is deposited in considerable quantities along the mar- 
gins of navigable streams and in the river beds between Charles- 
ton and Beaufort. When a deposit is located it is first thoroughly 
prospected by boring with a core boring machine, as by this means 
the depth of the bed is ascertained as well as the grade of the 
various layers of phosphate encountered. 

The mining is hydraulic. Powerful streams of water are 
thrown against the edge of the bed and the phosphate gravel 
together with the sand and clay is washed into a hole about 
10 ft. in diameter and 10 to 15 ft. deep. The gravel is sucked up 
from this hole by means of a pipe and run to the mill, which may 
be half a mile or more away. Here it is passed over screens 
which allow the fine silt and sand to escape while the phosphate 
pebbles are caught. This serves to wash the rock, and it is then 
passed through direct-heat rotary dryers and carried by belts 
to the storage bins, ready for shipment. 

Tennessee Brown Rock Phosphate. The Tennessee phos- 
phates occur almost entirely in Silurian and Devonian strata, but 
more particularly in the former, and in the transition strata 
between the two. In December, 1893, blue rock phosphate was 
discovered in Hickman County. The beds of brown rock in this 
vicinity, which are the finest phosphate deposits in the world, 
were not worked till later. Some 45,000,000 tons of this brown 
rock are estimated as being available for mining in this district. 
New fields are being continually opened up, railroads built and 
large quantities shipped. As the brown rock of this locality is 
gradually used, the vast blue rock fields of Maury, Hickman, and 
Lewis counties will come into active development. 

This brown rock lies in strata formation with layers of clay 
and earth as overburden. This overburden is stripped by hand 
or steam shovel and the soft wet phosphate taken out either by- 
hand or steam shovel. It is carried to the washers, where it is 
freed from the most of the clay and dirt. On account of the 
porous nature of this rock, the clay is disseminated all through 



FERTILIZERS 227 

it and it is very difficult to get rid of all the clay by the use of 
simple log washers. Many types of washers are used, the most 
efficient being the form used in cleansing glass-makers' sand. 
This is done by pumping the fine material through pipes having 
sharp angles, where the pressure is greatly increased. The clay 
is washed out in this manner and the clean rock is finally deliv- 
ered to very deep settling tanks, where the muddy water hold- 
ing the clay in suspension is drawn off and the heavier rock, 
which settles after the tank is filled, is dried in rotary direct- 
heat dryers and is then ready for shipment. 

Thomas or Belgian Slag. Thomas or basic slag is a by- 
product in the modern method of steel manufacture from ores 
containing noticeable quantities of phosphorus. The process of 
removing the phosphorus from the ore was first discovered by 
the English engineers Gilchrist and Thomas and consists in add- 
ing to the converter containing the milled ore a definite quantity 
of freshly burnt lime, which, after powerful reaction, is found to 
be united with the phosphorus and swims on the top of the 
molten steel in the form of a slag. 

The fertilizing value of the slag was not recognized for a long- 
time. A considerable portion of its phosphoric acid was found 
to be soluble in dilute citric and carbonic acids, which led to suc- 
cessful field experiments. The only preparation of the slag for 
fertilizer purposes when its value was first recognized, consisted 
in having it finely ground in specially prepared mills so that 
To per cent would pass a sieve of 0.17 mm. mesh. This require- 
ment was suggested by M. Fleischer, who used the slag with 
much success in improving marsh and meadow lands. 

Bone. Bones consist of two distinct kinds of matter. One 
is mineral in character and consists of phosphate of lime or true 
bone phosphate; the other is organic, consisting of a flesh-like 
matter called ossein, which contains much nitrogen. 

POTASH. This term as applied to fertilizers always means 
the oxide of potassium. It is not found as such in fertilizers, 
but as either chloride, sulphate, nitrate or carbonate of potassium, 
or as organic potash. 

Potash soluble means the actual K2O soluble in water, and 
is the only kind considered in fertilizers. 

Crude Stock Furnishing Potash. Muriate or chloride, 
kainit, containing both muriate and sulphate; sulphate; double 
manure salt; the double sulphate of potash and magnesia; less 
important salts are carnalite, krugite, sylvanite. Carbonate of 



228 ELEMENTS OF INDUSTRIAL CHEMISTRY 

potash, such as wood ashes. As organic potash, tobacco stems 
and ashes, cotton-seed meal. As nitrate, potassium nitrate. 

Alunite, the hydrated sulphate of potash and alumina, is found 
in many places in the West and work is being done on it to deter- 
mine its availability as a source of potash. It has been found 
that after ignition and leaching, over 90 per cent of the, potash 
can be recovered as sulphate. It appears to be a very promising 
source for future supply of this material. 

PEAT FILLER. Dried humus or peat is used as a filler on 
account of its absorbent properties, but its use is prohibited by 
some States if the nitrogen content is included in the nitrogen 
of the fertilizer, because this nitrogen is unavailable. 

how to Calculate Amounts of Material to be Used 
in Making a Complete Fertilizer of Definite Com- 
position FROM THE RAW MATERIALS. Suppose that we 
desire to make a fertilizer having the composition: nitrogen 4 
per cent, phosphoric acid 8 per cent, and potash 10 per cent. 
Suppose in addition we have on hand the following materials: 
nitrate of soda containing 16 per cent nitrogen, acid phosphate 
containing 15 per cent available phosphoric acid, and muriate 
of potash containing 50 per cent actual potash (K2O). How 
many pounds of each of these materials will we require? 

To contain 4 per cent nitrogen, the ton must contain 80 lbs. 
Nitrate of soda contains 16 lbs. of nitrogen in every 100 of the 
nitrate, and hence 500 lbs. of nitrate of soda would be required 
to make up the 80 lbs. 

To contain 8 per cent phosphoric acid, the ton must contain 
160 lbs. The phosphate contains in every 100 lbs. 15 lbs. of 
phosphoric acid and hence 1067 lbs. of the acid phosphate will 
be required to furnish 160 lbs. available phosphoric acid. 

To contain 10 per cent potash the ton must contain 200 lbs. 
Our muriate contains in every 100 lbs. 50 lbs. actual potash, 
and hence 400 lbs. will be required to give the 200 lbs. 

We should then have the following: 

500 lbs. nitrate of soda, 
1067 lbs. acid phosphate, 
400 lbs. muriate of potash, 

or a total of 1967 lbs. Now to make it up to 1 ton we simply 
add 33 lbs. of any inert material such as dirt, for instance, and 
we then obtain 1 ton of fertilizer of the desired composition. By 



FERTILIZERS 229 

adding 1 more ton of " filler " we should have 2 tons of fer- 
tilizer of the following composition: nitrogen, 2 per cent, phos- 
phoric acid, 4 per cent, and potash, 5 per cent. 

Now for the more complicated example suppose we wish to 
make a fertilizer of the same composition, but instead of having 
three materials, each containing only one ingredient, suppose we 
have on hand Peruvian guano, containing 3 per cent nitrogen, 
18 per cent phosphoric acid, and 3| per cent potash. 

To give us 160 lbs. (8 per cent) of phosphoric acid we shall 
require about 900 lbs. of this guano. Nine hundred pounds 
would also supply 27 lbs. of nitrogen and 31 lbs. of potash. But 
we require 80 lbs. of nitrogen and 200 lbs. of potash in all, or 
53 lbs. more nitrogen and 169 lbs. more potash to complete the 
mixture; 384" lbs. of nitrate of potash analyzing 14 per cent 
nitrogen and 44 per cent potash would supply this 53 lbs. nitro- 
gen and also the 169 lbs. potash, therefore we have 

Nitrogen. Phos. Acid. Potash. . 

900 lbs. guano containing 27 lbs. 160 lbs. 31 lbs. 

and 

384 lbs. nitrate of potash 53 lbs. 169 lbs. 

or total of 

1284 lbs. containing 80 lbs. 160 lbs. 200 lbs. 

Now by adding 716 lbs. of filler we have 1 ton of fertilizer of 
the desired formula. 

For a third example, suppose we have the following materials : 

1st, one containing 3 per cent nitrogen, 18 per cent phos. acid, and 3| per cent 

potash; 
2d, one containing 6 per cent nitrogen, 9 per cent phos. acid and 2 per cent 

potash; 
3d, one containing 50 per cent potash; 

we would then take 

1st. 300 lbs. containing 

2d. 1200 lbs. containing 

3d. 332 lbs. containing 

Total 1832 81 162 200 

By adding 168 lbs. of filler we then have 1 ton of our fer- 
tilizer. 

A filler in common use is obtained from garbage extracted 



Nitrogen. 


Phos. Acid. 


Potash. 


9 lbs. 


54 lbs. 


10 lbs. 


72 lbs. 


108 lbs. 


24 lbs. 
166 lbs. 



230 ELEMENTS OF INDUSTRIAL CHEMISTRY 

for the grease it may contain. The pressed and dried material 
has practically no value from its nitrogen or phosphorus content, 
although the tankage is very heavy in soluble material. 

These methods of calculation of formulae are simply given as 
examples; as a matter of fact, probably not over 5 per cent of 
all the complete fertilizer manufactured contains " filler " in the 
sense in which it is given above. When low-grade fertilizers are 
to be made, they are compounded from low-grade raw materials 
that will, without the use of fillers, or with only a very small 
amount, give the formula desired. 



CHAPTER X 
ILLUMINATING GAS 

CLASSIFICATION. The industrial gases in use at the present 
time may be divided, roughly, into three general classes — coal 
and carbureted water gas and their various mixtures; the dif- 
ferent classes of oil gas, acetylene, gasoline gas; and producer 
gas. The first class is by far the most important from an illu- 
minating standpoint, while producer gas is, of course, of the 
greatest importance for fuel and power use. The other gases 
are generally employed in special cases where the use of the first 
class is impossible or inconvenient. 

Manufacture of Coal Gas. Coal gas is the result of the 
destructive distillation of bituminous coal in highly heated fire- 
clay retorts. The retorts vary considerably in cross-section, 
length and method of heating. They are usually set in groups 
of from six to nine retorts in what is known as a " bench," and 
the group of " benches/' varying with the capacity of the plant, 
is known as the " stack." In a few of the older and smaller 
plants the retorts are heated by a direct fire of coke or coal, but 
in the more modern and larger plants they are heated with pro- 
ducer gas. These retorts may be set either in a horizontal, 
inclined or vertical position, but in the latter cases the method 
of charging and discharging is different from that of the former. 
The object, however, in any case is to drive off the volatile matter, 
which consists principally of gas. 

In the manufacture of coal gas, coal with a high volatile 
content is preferred; that is, a coal belonging to the bituminous 
series according to the usual method of coal classification. 

Horizontal Retorts. In operating the horizontal retorts, Fig. 
74, the coal is placed in position by means of a charging machine, 
although formerly this was done by hand. The retort being 
filled about two-thirds full of coal, the door is closed and sealed. 
The bench is so arranged that the flame from the burning fuel 
heats the firebricks supporting the retorts. The time necessary 
to drive off the gases from the coal varies from six to eight hours / 

231 



232 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



at the end of which time only the residue of coke is left in the 
retort. The coke on being drawn from the retort is either 
quenched with water or allowed to fall into the furnace used 
for heating the retorts. 

The gases as they leave the retort pass up through ascension 
and dip pipes into the hydraulic main. From here the passage 




Fig. 74. 

of the gas will be considered after taking up the other methods 
of production 

Inclined Retort. In this form of apparatus the retorts are 
set at an angle. The charging is done by allowing the coal to 
run in at the elevated end directly from the storage bins; while 
the discharging is accomplished by removing the door at the lower 
end. Less labor is necessary for inclined retorts, but it is claimed 



ILLUMINATING GAS 



233 



by some that the yield of gas is not so great. The gas passes 
from the bottom of the retort through ascension pipes into the 
hydraulic main. 

Vertical Retorts. As the name indicates the retorts are built 
in a vertical position, illustrated in Fig. 75. The three retorts 







Ftg. 75. 

are charged at one time, the coke having been removed from the 
bottom by electrically operated machinery. The heating is 
accomplished by means of gas producers having large grate areas 
with primary and secondary air control. The gases from the 
three retorts, as shown in the illustration, pass through the 
ascension pipe to the b^draulic main. 

The ascension pipe bridge and dip pipes are provided with 



234 



ELEMENTS OF INDUSTKIAL CHEMISTRY 



removable covers so arranged that they may be readily cleaned 
of deposits of tar and pitch which accumulate in them and must 
be constantly removed. 

The producer is provided with grate bars and cleaning doors 
and is charged with hot coke as it is drawn from the retorts 
through the charging door on the upper floor level. The primary 
air enters through regulation shutters at the front of the bench, 
passes around the lower waste gas flues and hence beneath the 
grate. Rising through the fuel it combines with the carbon, 
forming producer gas. Steam is admitted beneath the grate to 
soften the clinkers and control their formation by lowering the 
temperature of the fuel bed. 

As the producer gas rises through the nostrils into the com- 
bustion chamber it meets the secondary air which is admitted 
through regulating shutters below and at the front of the bench. 




* Cyanogen Scrubber 
Fig. 76. 



The air travels through firebrick ducts in what is known as the 
recuperator , where it passes horizontally to the right and left and 
upward and is heated by the waste gases to a temperature of 
from 1600 to 1800° F., practically attaining the temperature of 
the waste gases. 

As the combustion takes place the hot products of combus- 
tion rise around the retorts to the top of the combustion chamber 
and are then drawn down and toward the front of the bench where 
they enter the waste gas flues in the recuperator, passing hori- 
zontally front and back and downwards giving up their heat to 
the incoming secondary and primary air. The waste gases finally 
pass to the back of the bench and hence to the stack, the draft 
of which is controlled with a damper set at a convenient point 
in the recuperator. 

The gas as it issues from the coal passes out through the 
mouthpiece and up the ascension pipe, and by means of the dip- 
pipe enters the hydraulic main. This acts as a seal to prevent 



ILLUMINATING GAS 235 

the gas escaping from the hydraulic main back into the retort 
when the mouthpiece is open for charging or discharging. Fig. 
76 shows the general plan of coal-gas plant. 

Ordinarily, there is an ascension pipe for each retort, but in 
some cases one ascension pipe serves three retorts, which are set 
directly above one another. This system is, of course, only 
applicable where the retorts are charged and discharged simul- 
taneously by machinery. 

Hydraulic Main. The desirability of the use of a liquid seal 
in the hydraulic main is subject to some question, and there are 
a number of methods proposed and in use whereby this seal may 
be lowered after the retort has been charged, thus putting the 
retort in direct connection with the hydraulic main, and then 
raising it' so that the retort is sealed off when the lids are opened 
for charging and discharging. Valves of different design have 
also been used for this purpose. 

When the hot gases come in contact with the liquid in the 
hydraulic main, a certain amount of tar is deposited; this is 
removed automatically from the main in order that it may not 
come into direct contact with the gas, and thus cause a deterior- 
ation of the candle-power. 

The crude gas leaves the hydraulic main at a temperature 
of from 65 to 75° C, and contains a number of impurities — tar, 
ammonia, sulphureted hydrogen, organic sulphur compounds, 
naphthalene and cyanogen — which must be removed in whole or 
in part before the gas is considered ready for distribution, and, 
furthermore, the gas must be brought down to the ordinary 
temperature. 

Condensers. When the gas leaves the hydraulic main it con- 
tains in addition to the imparities just mentioned a very complex 
mixture of hydrocarbons of widely varying boiling points, in 
addition to the water vapor with which it is practically saturated. 
Some of the hydrocarbons are fixed gases at the ordinary tem- 
peratures while in the others may be vapors, liquids or solids; 
while practically all are mutually soluble in each other and to 
some extent in water. As much of the illuminating value of the 
gas is due to the vapors of the benzol homologues it is important 
that these be retained in the gas as far as possible, while on the 
other hand the heavier hydrocarbons, especially naphthalene, 
must be removed as far as possible on account of their interference 
with succeeding stages of the purifying process or with the dis- 
tribution of the gas itself. 



236 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



At the temperature at which the gas leaves the hydraulic 
main, the tar exists principally as a fog, and also as a vapor which 
will condense with a lowering of the temperature. This is effected 
in the primary condensers, one form of which is illustrated in 
Fig. 77. The cooling agent may be either water or air. In a 
recent system the cooling water is sprayed through the gas, 
assisting in the removal of the tar, and the water is then freed 
from tar, cooled and recirculated. 

To? Extractor. On leaving the primary condensers, in which 
some of the tar is deposited, the gas is passed into some form of 





Fig. 77. 



Fig. 78. 



tar extractor, the usual form being that of the P. & A., which 
consists, as shown in Fig. 78, of a drum composed of a series of 
perforated sheets consisting of alternate series of small holes and 
blanks so arranged that the blank spaces in one set of sheets 
opposes the perforated sections in the adjoining sheets. Another 
form of apparatus is known as the washer-scrubber. In this, 
the gas passes through a number of small openings into contact 
with ammonia liquor, the action of the water causing the tar 
particles to coalesce and be condensed. It is found that the 
most efficient operation for the removal of tar requires a tem- 
perature of from 105 to 115° F. 



ILLUMINATING- GAS 



237 



Exhauster. The gas is now passed through the exhauster, 
Fig. 79, which operates to maintain a constant pressure in the 
retorts and to furnish the pressure 
necessary to overcome the resist- 
ance of the train of purifying ap- 
paratus, and to force the gas into 
the storage holder. 

Scrubber. From the exhauster 
the gas passes into the naphthalene 
scrubbers. These scrubbers, Fig. 
80, are composed of horizontal 
cylinders divided by a number of 
vertical partitions. A central shaft 
carries a disk made up of a large 
number of short wooden rods set 
parallel to the axis of the shaft, 
and arranged so that as they re- 
volve they dip into the contents 
of the scrubber, and on rising 
present a large wetted surface in 
contact with the stream of gas. 
A heavy tar oil, such as anthracene 

oil, water gas tar or vertical retort tar, is the material generally 
used for the removal of naphthalene. 




Fig. 79. 




Fig. 80. 



When cyanogen is extracted it is usually removed by means of 
a washer similar to the naphthalene washer. The solutions used 



238 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



vary according to the processes employed, but they usually con- 
sist of an alkaline solution of ferrous sulphate. The gas now 
passes to the ammonia scrubbers, similar to naphthalene 
scrubber. In order that the absorption of ammonia by water, 
which is usually used to remove it, will be complete, it is 
necessary that the temperature of the gas be reduced to about 
60°. This reduction in temperature is secured in the second- 
ary condensers; these are always water cooled in order to 
secure the low final temperature that is necessary. 

This absorption was formerly carried on in large towers filled 
with cobble stones or boards, or other devices exposing a large 
surface, which was kept moistened by water or weak liquor 
passing down from the top. This form of scrubber has been 
generally replaced by the more compact washer-scrubber similar 
in construction to that described for cyanogen removal. In 
these mechanical scrubbers the ammonia is completely removed 
by the use of from 10 to 15 gallons of water per ton of coal car- 
bonized, and as the gas is at the same time brought into contact 
with the concentrated ammonia liquor at the inlet end of the 
scrubber, a considerable proportion of sulphureted hydrogen 
and carbon dioxide is also removed. 

Ammonia Liquor. The ammonia liquor and tar that are 
removed at the different points in the condensing and purifying 
system are collected and passed through what is known as a 
separator. In this apparatus, the stream of mixed liquor in pass- 
ing through the separator 
is baffled and turned in its 
course a number of times, 
so that the tar, which has 
a specific gravity of 1.2, and 
higher, falls to the bottom 
and may be removed, while 
the liquor rises to the top 
and may be pumped orV 
to the ammonia storage 
tanks. 

The remaining impuri- 
ties in the gas are sulphur 
eted hydrogen and organic sulphur compounds. 

Purifiers. The sulphureted hydrogen is generally removed 
by passing it through large vessels, called purifiers, Fig. 81, where 
it is brought into contact with some form of ferric oxide. There 




Fig. 81. 



ILLUMINATING GAS 239 

is considerable discussion as to the exact reactions which take 
place. The probable reactions are 

Fe 2 Os + 3H 2 S = Fe 2 S3 + 3H 2 
and 

Fe 2 3 +3H 2 S = Fe 2 S+S+3H 2 0. 

It seems likely that these two reactions take place simultaneous^, 
and the proportions of ferric and ferrous sulphide formed are 
dependent upon the nature of the oxide and other conditions. 
It is said to be in the relation of three parts ferric to five parts 
ferrous sulphide. When the oxide has become saturated it is 
removed from the purifiers and exposed to the air, where, under 
the influence of the atmospheric oxygen, ferric oxide is formed 
and sulphur set free. 

In order to take advantage of this reaction, small quantities of 
air are sometimes admitted to the crude gas before entering 
the purifiers, the oxygen in which reacts with the partially fouled 
purifying material, and thus considerably increases the length of 
time before it is necessary to remove it. 

The purifying material is composed of either a natural ferric 
oxide or, as is generally the case, made by coating shavings, 
planer chips or com cobs with some form of ferric oxide. 

The efficiency of the purifying material thus made seems to 
depend upon the nature of the ferric oxide; the more active 
oxides are apparently colloidal in nature. Where the oxide is 
made by rusting iron borings on the chips the organic acids in 
the wood act as protective colloids and result in the formation 
of varying percentages of the iron in the colloidal form. 

Certain natural oxides and some of the artificial oxides that 
result as by-products in the manufacture of alums are found to 
have a considerable proportion of their iron content in the form 
of a colloid ferric hydroxide. Apparently it is the enormous 
surface that is presented by these colloidal oxides that explains the 
increased chemical efficiency of oxides in this state. 

In the older type of pufifiers the oxide was contained in 
shallow cast-iron boxes provided with water-sealed lids, the oxide 
being carried on wooden trays in two layers of about 30 ins. each. 
These boxes were arranged usually in sets of four or six, and 
so connected with valves that the sequence of boxes could be 
varied at will, and any box could be removed from service for 
cleaning. 



240 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



It has now been found more economical to put the oxide into 
only two or three large boxes, building these either of steel or 
concrete out of doors, and th\ s saving expensive buildings. 

In testing the operation of the purifiers, we find that the first 
box removes the greater portion of the hydrogen sulphide, and 
that as the percentage of sulphur decreases it becomes increas- 
ingly difficult to remove it. The purifiers are usually arranged, 
therefore, so that at least one box is kept filled with fresh and 
active oxide to retain slight traces of sulphureted hydrogen which 




Fig. 82, 



might pass through the other boxes which remove the bulk of 
the Lr purity. 

WATER GAS. The manufacture of water gas depends upon 
the decomposition of steam by the action of incandescent carbon. 
The gas made by this reaction is called " blue gas," and while it 
has a heating value of about 300 B.T.U.'s per cubic foot it is non- 
luminous. In order to render the flame luminous it is necessary 
to add some hydrocarbon that will liberate free carbon in the flame. 
Many early patents were taken out to do this, but the process 



ILLUMINATING GAS 241 

did not become important until the Pennsylvania petroleums 
became commercially available. 

The modern apparatus is the development of the Lowe 
apparatus that was patented in 1872-75. In its present form 
it is a very efficient process, as every feature has been considered 
both from a theoretical and operative standpoint. The supply 
of air and steam is metered. The temperatures in the fixing 
chambers are controlled with electric pyrometers and the sensible 
heat in the off-going blast and illuminating gases is recovered 
in greater part in economizer boilers that return sufficient steam 
to operate the plant. 

The apparatus shown in Fig. 82 has a capacity of 1,500,000 
cu.ft. per day, but units having a capacity of 3,000,000 cu.ft. 
per day are in regular operation. 

Operation. The operation of a modern plant is as follows: 
The generator is charged with the fuel through the coaling door 
A. After ignition, it is raised to a point of incandescence by 
a blast of air supplied under a pressure of from 16 to 20 ins. 
through the blast pipe B, passing through the interlocking 
valve C, which is so connected that it will be impossible for the 
blast and the gas to come together and thus cause explosions. 
The air passes down through the Venturi meter D and is controlled 
by the valve E, where it enters the generator beneath the grate, 
passing through the fuel bed, where the reaction C+02 = C02 
and C02+C = 2CO. The temperature of the fuel rises rapidly 
and a certain amount of producer gas is formed. This passes 
through the pair of valves FG, F being open during the blast, 
through the connection H, into the carbureter. The carbureter, 
which is a firebrick-lined vessel filled with checker-brick, is 
brought to the required temperature by the sensible heat in the 
blast products, and by the combustion of their CO by means 
of a secondary supply of air entering through the valve I. From 
the carbureter the products pass downward and up through 
the superheater, out through the valve K to the stack. When 
it is desired, the tertiary supply of air can be admitted through 
the valve J at the base of the superheater, causing further com- 
bustion, if desired, and local heating in this part of the apparatus. 

When the carbureting and superheating vessels have been 
brought to the proper temperature, the fuel in the generator is 
very highly heated. The air blasts are cut off in the order 
J, I and E. The stack-valve K is closed by means of lever L, 
and steam is introduced by means of the valve M and the steam 



242 ELEMENTS OF INDUSTRIAL CHEMISTRY 

meter beneath the grate. The steam passes up through the 
bed of incandescent fuel, where the reactions C+H20 = H2+CO, 
and the further general water-gas reactions CO+H20 = C02+H2 
take place. The water gas passes into the carbureter, where it 
meets the carbureting oil, which is measured by the meter Q 
and is sprayed into the carbureter through R. The sensible 
heat of the water gas and the high temperature in the surface 
of the checker-bricks vaporize the oil. The mixture of water 
gas and oil vapors then passes down through the carbureter, 
where the vaporization is completed, a considerable portion of 
the vapors decomposed and to some extent polymerized into 
fixed gases. Passing from the base of the carbureter up through 
the superheater, the temperature of the checker-brick of which is 
very carefully regulated, the decomposition of the oil vapors is 
carried to the most advantageous point, and the resulting mixture 
is composed of fixed gases, some condensible vapors and a small 
quantity of complex hydrocarbons, known as water-gas tar. 

These pass out through the connection to the valve K, through 
the dip-pipe S into the wash-box, which acts as a hydraulic seal 
and prevents both the escape of the products of combustion dur- 
ing the blasting period and the return of the illuminating gases. 
In contact with the water in the wash-box, the temperature of 
the gas is reduced from 1200 to 1300° F. to about 190° by the 
vaporization of the water, and some of the tar is deposited. The 
gases pass out of the wash-box through the connection to the base 
of the scrubber, and rise through the staggered nest of wooden 
trays, where the entrained solid matter, considerable water, 
and some tar are deposited by impingement and the temperature 
is somewhat reduced. From the top of the scrubber it passes 
into the top of the condenser through the water-cooled tubes. 
By means of the cooling water the temperature is reduced to 
150° F., and it passes out of the connection Z to the relief 
holder. 

Fuel Used. The fuels used in the manufacture of water gas 
are anthracite and semi-anthracite coals and the various grades 
of coke. As they are used primarily as a source of carbon they 
should be high in fixed carbon, containing not over 7 per cent of 
volatile combustible, as some of this is liable to loss during the 
blasting period. The ash should be low and of high fusing point 
so that the formation of clinkers may be reduced to a minimum, 
although fuels containing as high as 25 per cent of very fusible 
ash can be utilized successfully. The fuel should be uniform 



ILLUMINATING GAS 243 

in size to permit the free flow of the blast and steam and it should 
be low in moisture and sulphur. 

Enriching Oils. The oils available for enriching purposes 
vary in their composition in the different fields. The oils from 
Pennsylvania, Ohio, Indiana, and Illinois are composed prin- 
cipally of the paraffine and olefine series; the oils from Kansas 
and Oklahoma differ somewhat according to their gravity, 
the lighter oils containing considerable paraffine while the heavier 
oils contain some paraffmes but principally naphthenes. 

The gas as it leaves the machine goes to a relief holder, then 
to shaving scrubbers, then to the purifiers and finally to the 
gasometers for distribution. These pieces of apparatus are prac- 
tically the same as used for coal gas. The tar, however, is of an 
entirely different nature. 

A new form of water gas apparatus, which is largely replacing 
the Lowe Machine is that known as the Williamson Machine. 
This machine has the carbureter and superheater above the fuel 
bed. By this means it is possible to economize on space and cost 
of installation. The working of the machine is the same as for 
the older type. 

ALL-OIL WATER GAS. Directly related to the manufacture 
of carbureted w r ater gas is the so-called all-oil water gas which 
is used so extensively on the Pacific Coast where there is an abun- 
dant supply of cheap fuel oil. 

In the present form of apparatus which is illustrated in 
Fig. 83, there are two firebrick-lined shells in the form of a U, 
with one leg longer than the other, the shorter leg serving as the 
primary generator while the longer leg serves as a superheater. 
Both shells are filled with checker-brick. The gas take-off for 
the blast gases is at the top of the longer leg while the illuminat- 
ing gas take-off is in the middle. 

In the operation of the set, oil and steam are blown into the 
top of the primary generator while the blast is admitted in the 
center. The blast is turned on for about three minutes before 
the oil at a pressure of about 9 ins., at the end of this time the 
oil is turned on at a pressure of about 8 lbs., the atomizing 
steam at 35 lbs. The heating period is about twelve minutes; 
at the end of this time the blast is cut off, the valve opened con- 
necting with the wash-box, and the gas-making oil is injected as 
before, with steam, through another set of nozzles. The gas- 
making nozzles are located both in the primary generator and 
also in the top of the secondary generator, so that the flow of 



244 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



oil through the machine can be regulated according to the heat 
carried in the checker- work in all parts of the set. The oil is 
admitted to the top of the primary generator at first quite rapidly, 
it is then gradually reduced during the run until at the eighth 
minute it is flowing at about one-third the initial rate per minute. 
The oil is admitted to the secondary generator at a slightly slower 
rate and is gradually reduced in the same pro :ortion. The last 
two minutes of the run the oil is cut off and the steam pressure 
is raised to 100 lbs., and allowed to remain at this pressure for 
two minutes in order to purge the machine. 

The heats in the machine are controlled by the appearance 




Fig. 83. 



of the overflow from the wash-box, the presence of tar showing 
that the heat is too low, while lampblack from the overflow in 
the first scrubber shows that the heat is too high. The make 
of gas per minute during the run is a very good indication of the 
heats carried and is an indqx to the proper length of the run. 

In the larger machines about 16 per cent of the total oil used 
is burned during the heating runs; so that where the total oil 
per thousand runs abou: 8^% gallons, about 1-^- gallons per thou- 
sand are used during the heating run and 7^ gallons during the 
gas-making run. 

In general this gas resembles coal gas in many of its con- 
stituents much more closely than it does water gas. But there 



ILLUMINATING GAS 



245 



is eveiy reason why this should be so, as both of these gases are 
formed by the pyro-condensation of hydrocarbons. 

The formation of the all-oil water gas is almost identical 
with the second and third stages of the coal-gas distillation except 
that in the case of the oil gas the temperature conditions and 
time of contact are under much more exact control. In general 
all that has been said previously in reference to the decom- 
position of the hydrocarbons applies with equal force in the 
manufacture of oil gas in this apparatus. 

PlNTSCH GAS. Another commercial adaptation of oil gas 
is that known as Pintsch gas. Iintsch gas is simply an oil gas 
compressed to about ten atmospheres and was developed origi- 
nally for the lighting of railway passenger cars. The Pintsch 
patents were taken out about 1870. 

In this system the oil is first decomposed in a double iron 
retort, set in a regular coal-gas 
bench, an outline sketch of 
which is shown in Fig. 84. 
The oil is introduced at the 
front of the upper retort and 
falls upon a movable tray, 
which collects most of the car- 
bon formed. The gas and 
vapors thus produced pass to 
the back of the upper retort 
down and out through the 
lower retort to a hydraulic 
main located in front cf the 
bench. The crude gas is passed 
through a dry scrubber, con- 
denser and purifier and after 
metering is collected in a low- 
pressure holder, very similar 
in all respects to the processes 
employed in condensing and 

purifying coal gas. The gas is then compressed, generally in a 
two-stage compressor, into the storage cylinders. 

Blau GAS. Another modification of the Pintsch gas is 
known as Blau gas. In this process the oil is decomposed in the 
retorts, as in the manufacture of Pintsch gas. The gas is purified 
and then compressed to 100 atmospheres, so that the greater 
portion of it liquefies. Under this pressure the liquefied hydro- 




Pic. 84. 



246 ELEMENTS OF INDUSTRIAL CHEMISTRY 

carbons probably absorb and hold in solution some of the olefines 
and paraffines that would normally be gases at this pressure. 
The oil is gasified at rather a lower temperature than that ordi- 
narily employed in the manufacture of oil gas. The fixed gases 
that are left after compression are used in operating the machinery 
necessary in the manufacturing operations. The liquefied gas has 
a specific gravity referred to water of .59. The liquid is sold 
ordinarily in seamless steel flasks that hold 45 and 10 kg. The 
gas is first expanded from 100 atmospheres down to about 10, 
and is then expanded again to 10 or 12 ins. water pressure. One 
gallon of the liquefied gas will yield about 28 cu.ft. of expanded 
gas. 

GASOLINE GAS. Gasoline gas is a mixture of atmospheric 
air and light hydrocarbon vapor in varied percentages generally 
above the explosive limit. This gas has been developed to meet 
the requirements of isolated localities where the quantity of gas 
required is small, so that the installation of the usual form of 
coal or water-gas apparatus would not be profitable. There are 
two general systems used in its manufacture ; one system operates 
in the cold while the other system employs heat to aid in the 
vaporization. Gasoline or carbureted-air gas differs from the 
ordinary forms of coal gas, water gas or oil gas, due to the fact 
that it is a simple mixture of the vapors of a liquid hydrocarbon 
which is not changed chemically in the vaporization. In the 
cold process, where the air is not heated, a very light grade of 
gasoline must be employed, while in the system employing steam 
or other source of heat to assist in the evaporation the less expen- 
sive naphthas may be used. 

ACETYLENE. The use of acetylene as an illuminant in small 
towns and for isolated plants has developed to a very consider- 
able extent during the last few years, owing to the standardization 
that has taken place in the manufacture of calcium carbide. In 
producing this gas it is only necessary to treat the carbide with 
water, held in a suitable container, and pass the gass through 
pipes to the service point. 



CHAPTER XI 
COAL TAR AND ITS DISTILLATION PRODUCTS 

COAL TAR. This is the black, foul-smelling, onV mixture 
which separates from the gases formed in the destructive dis- 
tillation of coal. The raw tar is composed of light oils, pyridine 
bases, phenols, naphthalene, anthracene, heavy oils, pitch, com- 
plex organic compounds insoluble in benzene, and known as free 
carbon, water, ammonia, and dissolved constituents cf the gas. 
As there is little prospect that the principal object of the destruct- 
ive distillation of coal will be the production of tar, there has 
been little research upon the conditions necessary to produce 
tars of the most desirable properties. It varies greatly in com- 
position and may be divided into retort-gas tar and oven-gas 
tar, according to its method of production. 

Retort-gas Tar. This tar is obtained as a condensation 
product in the hydraulic mains, scrubbers, or condensers, in the 
manufacture of coal gas for illuminating purposes. It is less 
fluid and contains less of the lighter hydrocarbons, more naphtha- 
lene, anthracene and their accompanying oils, and more free car- 
bon than tars from some other sources. The composition varies 
with the heats and coals employed. The lower the carbonization 
temperature of any coal the more fluid the tar and the lower 
the free carbon content. 

The specific gravity of the dry (water-free) tar varies from 
1.10 to 1.25 or even somewhat higher. 

It contains from 18 to 40 per cent of free carbon and yields 
on distillation from 1 to 5 per cent of light oil to about 200° C, 
30 to 50 per cent heavy oil, including naphthalene, anthracene, 
phenols, and accompanying oils, from 200° C. to the coking tem- 
perature, and from 45 to 65 per cent coke; or if distilled to pitch 
the yield would be light oil 1 to 5 per cent, heavy oil 25 to 40 per 
cent, and pitch 50 to 75 per cent. 

Oven-gas Tar. This material is obtained as a by-product 
in the distillation of coal in retort coke ovens. It is similar to 
retort-gas tar, except that it is more fluid. It contains more of 

247 



248 ELEMENTS OF INDUSTRIAL CHEMISTRY 

the hydrocarbons, and considerably less free carbon, which latter 
usually runs from 5 to 20 per cent. 

The composition of course changes with the coal, with type 
of oven, and with the coking temperature. 

Producer-gas tar, owing to the method of production, usually 
consists of large percentages of water and free carbon, together 
with a very small amount of oils and yields, when distilled, a 
very friable pitch entirely unsuitable for the purposes for which 
pitch is made, and therefore of no commercial importance. 

* Blast-furnace tar is essentially a low-heat tar, being pro- 
duced in blast furnaces fed with coal instead of coke and the 
gases liberated from the coal come in contact with a cooler zone 
as soon as formed. It usually has a specific gravity between 
0.94 and 1.000 and contains more phenoloid and basic sub- 
stances than ordinary coal tar. These phenoloid substances 
resemble those obtained from the destructive distillation of 
wood and lignite and amount to from 5 to 10 per cent of the 
tar, while 1 to 2 per cent is the usual amount in ordinary coal 
tar. 

It also contains from 2 to 5 per cent of basic bodies and about 
16 per cent of paraffine oils which solidify on cooling. These tars 
are entirely different from the ordinary coal tar and not suited 
for the same purposes. 

Water-gas Tar. From the manufacture of carbureted water 
gas for illuminating purposes, the car obtained differs mainly from 
coal tar in the entire absence of tar acids (the phenol group), 
ammoniacal liquor, and in the small amount of free carbon present, 
which is usually less than 2 per cent in these tars. 

The specific gravity varies from 1.005 to 1.15, but is usually 
between 1.03 and 1.12 in tars from the larger and more care- 
fully supervised works. 

Dry water-gas tar, when distilled, yields from 5 to 15 per 
cent of light oil to 200° C, 30 to 50 per cent of heavy oil from 
200° C. to pitch, and 35 to 60 per cent of pitch. 

Pintsch or Oil-gas Tar. This comes from the manufacture 
of oil gas used for railway lighting. It is similar to water-gas 
tar, but sometimes contains much larger amounts of free car- 
bon, frequently 25 to 30 per cent, or even more. 

APPLICATION OF TAR. Tar is little used in the crude state, 
but is refined by removing the water and more or less oil by 
distillation. In this condition it is used to saturate roofing 
felt, to coat roofs laid with plain tar felt, as a cheap paint, and 



COAL TAE AND ITS DISTILLATION PRODUCTS 249 

to coat wood which is to be buried in the ground. With more 
oil removed it is used as a binder in asphalt pavements and 




SandFIlIing 
Fig. 85. 




Fig. 86. 



tar-macadam roads. With an admixture of water, it is used to 
sprinkle telford and macadam roads to prevent dust. 



250 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Tars are separated into their valuable constituents by dis- 
tillation. The stills, Figs. 85 and 86, may be either horizontal 
or vertical cylinders set in brickwork and heated by direct 
fire similar to steam boilers. Stills vary in size and in design. 
Those with a capacity of 10,000 gallons are not uncommon, 
but most stills have less than half this capacity. The European 
practice is to use vertical stills with convex top and concave 
bottoms. 

The top and sides are constructed of half-inch boiler plate, 
while the bottoms are frequently from 1 to 1} ins. in thickness 
and are protected from the direct heat of the fire by a brick 
arch. The hot gases from the fire are led around the lower 
half of the still in flues. 

The American practice is to use horizontal stills heated on 
slightly less than half of their cylindrical surface protected 
by an arch directly over the fire and so designed that the portion 
of the shell heated may be readily replaced when damaged. 
The still is equipped with the usual worm, which may be made 
of either cast- or wrought-iron pipe with receivers, and with 
a pitch cooler. The objections to cast-iron worms are their 
numerous joints and greater weight. Since the development of 
electric welding wrought-iron worms may be made of any de- 
sired length with no joints to give trouble. Where high-carbon 
tars are worked, stills must be provided with suitable means of 
agitating to prevent the carbon becoming caked upon the heated 
part of the shell. Drag chains were formerly employed for 
this purpose, but compressed air or superheated steam is now 
more often used, as they serve to keep the still clean and assist 
in removing the high-boiling oils. 

DISTILLATION OF TAR. The operation of tar stills varies 
considerably at different works. The receivers are changed at 
different temperatures and therefore the products are not uni- 
form. In America it is the more common practice to fraction 
as light oil until the distillate commences to sink in water and 
as heavy oil or creosote oil from that point to pitch. Very 
little, if any, anthracene is made in this country, as most of 
the tar is run only to soft pitch with a melting-point between 
60 and 80° C. 

The European practice is different. From four to six frac- 
tions are taken before the pitch and a very large percentage of 
the tar is run to hard pitch. The following will show the most 
common fractions and the temperatures of the " cuts." 



GOAL TAR AND. ITS DISTILLATION PRODUCTS 251 

American Practice European Practice 

Light oil, or \ Till oil sinks in water First light oil, or \ T 11n o p 
Crude naphtha J about 200° C. First runnings ( ±0 iiU ^- 

SdtgMoil }noto2oo»c. 
Heavy oil, ] 90n o r Carbolic oil 200 to 240° C. 

Dead oil, or [ ZTLi+lL Creosote oil 240 to 270° C. 



Creosote oil J to pitch Anthracene oil 270 to pitch 

Pitch Residuum Pitch Residuum 

The tar is usually charged into the hot still (from the pre- 
vious run) . 

The fire is lighted when the charging is about half com- 
pleted. The fire must be carefully regulated till the rumbling 
or crackling noise in the still ceases, which denotes that the 
water has all been driven over. The firing can now be pushed 
so that the distillate runs at the rate of 200 to 400 gallons per 
hour. When the desired grade of pitch has been obtained, 
the fire is drawn and the pitch is run or drawn into the pitch 
cooler, a closed tank with a manhole having a loose-fitting, 
free-opening lid which, while it acts as a safety valve, prevents 
free access of air. The pitch, when sufficiently cooled, is filled 
directly into barrels for shipment or storage. 

The fraction to 200° C. contains water, ammoniacal liquor, 
crude benzols, pyridine bases, and a part of the naphthalene, 
heavy oil and phenols. The second fraction from 200° C. to 
soft pitch (about 270° C.) consists of phenols, naphthalene, 
heavy oil and some anthracene, though the greater part of the 
anthracene comes over above 270° C. If the distillation is con- 
tinued to hard pitch, a cut could profitably be made at about 
270° C.j above which point most of the anthracene and anthra- 
cene oil would be obtained. The treatment of the fractions 
as obtained by the American practice only will be considered 
with incidental allusions to the foreign methods. 

The light oil fraction is allowed to settle and the ammoniacal 
liquor or water is drawn off. The pyridine bases are not as a 
rule recovered in this country, but are allowed to remain in 
the heavy oil with the phenols. If it is desired to separate them 
the light oil is agitated with dilute sulphuric acid in a lead-lined 
cone-bottomed tank, fitted with a lead-covered propeller, usually 
supported entirely outside the tank, which mixes the contents. 
After the pyridine bases have been removed the oil is trans- 
ferred to a similar iron tank, in which, in order to remove the 
phenols, it is treated with caustic soda solution of about 1.116 



252 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



specific gravity. After the carbolates have been drawn off, 
the oil is charged in a still, of 2000 to 3000 gallons capacity, 
similar to a tar still, but having in addition a column and con- 
denser for fractionally condensing, Fig. 87, and washing the 



INVENT PIPE 



COLUMN 

OR 

DEFHLECMATOR 



EH 



. WWATER OVERFLOW 
. THERMOMETER 




/:? "^ 9 COILS 2)i"PIPE 
-COOLER WORM 



-2)4 WATER OVERFLOW 




Fig. 87. 



vapors coming from the still. The following fractions are usually 
taken : 

Crude 90 per cent benzol, to 95° C. 

Crude toluol, 95 to 125° C. 

Crude solvent naphtha, 125 to 170° C. 

Heavy naphtha, 170 to 200° C. 

Residue. 

The residue consists of naphthalene, heavy oil, and phenols 
if not previously extracted. It should be added to the second 
fraction from the tar still. 

In some works only three fractions are made in the light- 
oil still, the first two being combined and this fraction being- 
subjected before washing to another distillation in a steam- 



COAL TAR AND ITS DISTILLATION PRODUCTS 253 



heated column still. The fraction consisting of benzene, toluene, 
xylene, and their impurities, would be cut as follows: 

Crude 90 per cent benzene up to 95° C. 

Intermediate fraction (which is rerun) 95 to 105° C. 

Crude toluene 105 to 120° C. 

Crude solvent naphtha added to that fraction . 120 to 125° C. 

The purification of these fractions consists in the polymeriza- 
tion of the unsaturated compounds and the removal of the dis- 
solved polymerized hydrocarbons by 
distillation. The oil is treated with 
small portions of sul- 



successive 



sp.gr. 



in an 



phuric acid, 1.835 
agitator tank, Fig. 88, similar to 
the one used for pyridine extrac- 
tion. vThe agitator for washing with 
strong acid can be lined with lead. 
A better construction is of cast iron 
with leaded joints of the bell-and- 
spigot type, similar to those used on 



ifDiaxrraceMeij 
rieadftpe pron Pipe Water In lef 
-IironPipeWater 

Outlet to Dram 



| 'Standard CIPipe 



cast-iron water pipe, and with a 
conical bottom to permit of com- 
plete separation of the acid and the 
oil. The several small portions of 
acid are agitated with the oil, 
allowed to settle for a few minutes 
and the acid tar composed of spent 
acid and polymerized hydrocarbons 
drawn off. Care must be taken to 
remove the acid tar completely after 
the final application of acid. The 
acid necessary for a satisfactory 
purification of the oil shou.d be 
determined by a laboratory test 
after each addition of acid. If too little acid is used the tarry 
products are apt to separate and clog the draw-off, and if too 
much is used the spent acid will be very thin and fluid. A good 
wash is usually obtained when between \ and f of a pound of acid 
is used per U. S. gallon. This is applied in four to six successive 
portions. In this way a better wash and a larger yield will result 
together with a saving of acid. Formerly it was usual to wash 




Fig. 88. 



254 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



the oil two or three times with water, but as this serves only to 
reduce slightly the caustic soda necessary to remove all the acid 
remaining in the oil, and as it adds materially to the time required 
to complete the wash, it has been in most cases discontinued. 
The oil is finally treated with sufficient 10 per cent caustic soda 
solution to remove all traces of the acid. The washed oil is dis- 
tilled in a steam-heated still, which leaves behind, as a viscid 
mass, the polymerization products that were dissolved in the oil. 
This residue is reported to have some application in waterproofing 
paper. 

The final fractioning of the refined oils is conducted in steam- 
heated stills with columns similar to those used for the rectifica- 
tion of spirits. They consist of a series of plates, inclosed in a 
shell, with nozzles extending from their upper side, over which 
are inverted saucers or caps so designed as thoroughly to mingle 
the ascending vapors with the descending condensed oils and yet 
prevent foaming as far as possible. 

These columns were formerly made entirely of copper, as is 
the practice in alcohol rectification, but cast iron, wrought iron 
and steel are better materials, cost less and are not acted upon 
by the sulphur compounds contained in the oils. Columns fre- 
quently have as many as thirty sections to do the best work, 
though by far the greater part of the fractioning is done in the 
first ten or twelve sections. 

BENZOL. The crude benzols from light oil are colorless 
when freshly distilled, but they soon become a pale straw color 
and continue to darken for some time. They are known in 
the trade as crude or " straw-color " benzols of the various 
grades. 



Fraction. 


Specific 
Gravity. 


5-10% 


90% 


Dry. 


Flash-point. 


Straw-color benzol 

Crude 90 per cent benzol . 
Straw-color toluol 


} 


0.860-0.875 

0.860-0.875 

0.870-0.885 
0.925-0.940 


80° C. 

100° C. 

130° C. 
160° C. 


100° C. 

120° C. 

160° C. 
2.10° C. 


120° C. 

140° C. 

190° C. 
220° C. 


below 0° C. 
below 0° C. 


Crude solvent naphtha . 


22-26° C. 
43-45° C. 







These crude oils are chiefly used as solvents where their 
odors are not objectionable. Crude solvent naphtha and heavy 
naphtha are also used as thinners in certain cheap paints. 

Of the refined oils three are separated in a pure state, C.P. 



COAL TAP AND ITS DISTILLATION PRODUCTS 



255 



benzol, C.P. toluol, and xylol. The first two distill entirely within 
2° C, while the last is a mixture of the three xylenes and distills 
from 135 to 145° C. 

C.P. benzol or benzene, has sp.gr. .875 to .884. Freezing- 
point 4° C, boiling-point 80° C. It should distill completely 
within 2° C, be colorless and have the characteristic odor. It 
should not be colored on shaking with one-half its volume of C.P. 
sulphuric acid, 1.84 sp.gr., and the acid should be only slightly 
colored after standing for half an hour. It should be free from 
thiophens, contain only traces of carbon disulphide and from 
1 to 3 per cent of inert paraffines. 

TOLUOL. C.P. toluol or toluene has sp.gr. .865 to .876, 
boiling-point 110° C. It should be colorless and have the charac- 
teristic aromatic odor. It should not be colored by shaking with 
one-half its volume of C.P. sulphuric acid, sp.gr. 1.84, and the 
acid layer should not be colored deeper than a pale straw after 
standing for a half hour. In other respects it should answer 
the specifications for C.P. benzol. 

The following refined commercial fractions are colorless and 
should not be colored by shaking with one-half their volume of 
C.P. sulphuric acid, nor should the acid layer become colored 
deeper than a straw color in one-half an hour except in the case 
of 160 and 200° naphthas, when the acid may become colored 
deep red. 



Fractions 



Specific 
Gravity. 



Temperatures Noted in Distillation. 


80° C.-90 C. 


100° C. 


120° C. 


-10%-90-95% 


dry 




0% 


90-92% 


dry 


100° c. 


120° C. 


135° C. 


. 50-52% 


90-92% 


dry 


10-15% 


90-95% 


dry 


130° C. 


160° C. 


185° C. 


0-10% 


90-92% 


dry 


160° C. 


200° C. 


215° C. 


10-20% 


90-92%, 


dry 



Flash-point 



100% benzol 

90% benzol 

50% benzol 

Commercial toluol. . . 

Solvent or 160° 

naphtha 

200° naphtha 



. 870-0 . 880 
. 865-0 . 880 



0.862-0.876 
. 865-0 . 875 



. 860-0 . 870 
0.879-0.882 



below 0° C. 
below 0° C. 



below 0° C. 
below 0° C. 



22 to 26° C. 
42 to 45° C. 



The last two are not so well washed, therefore the acid be- 
comes more deeply colored. 

CREOSOTE OR HEAVY OIL. The fraction from the tar still 
between 200 and 270° C, and sometimes even higher, contains 
most of the phenols, naphthalene, anthracene, and the accom- 
panying oils. Anthracene will be found in large quantities 
only when the distillation of the tar is carried to hard pitch. 



256 ELEMENTS OF INDUSTRIAL CHEMISTRY 

If it is desired to remove the tar acids (phenols) the oil is 
agitated at a temperature of 50 to 70° C. with sufficient caustic 
soda solution sp.gr. 1.116, to combine with them. The alkaline 
liquor is allowed to settle and is drawn off, after which the oil is 
run into shallow tanks or pans, where a large part of the naph- 
thalene separates out as a mass of crystals when the oil cools. 
It is possible to treat the oil with successive portions of the caus- 
tic soda solution so as to obtain, first, an alkaline solution in 
which sodium phenolate preponderates; second an equally pure 
sodium cresylate; and third an unsaturated solution of caustic 
soda and sodium cresylate which is used as the first portion on 
the succeeding charge. 

The portion containing principally sodium phenolate is boiled 
by direct steam, and air is passed through the boiling liquid to 
remove naphthalene, hydrocarbon oils, and pyridine bases. In 
some works the distillate from the boiling carbolate is collected 
and worked for pyridine and naphtha, in which case the boiling 
is done by a fire-heated still instead of by direct steam. The 
distillate is collected until the purification is nearly complete, 
when the manhole is opened and direct steam and air blown 
through the liquor. After this treatment the carbolate of soda 
should be soluble in water without turbidity. The purified 
phenolate solution is allowed to become cold and is saturated 
with carbonic acid gas, usually obtained from the flue gases from 
the steam boilers. Finally, after the carbonate of soda solu- 
tion formed has been drawn off, the decomposition is completed, 
in a lead-lined tank, by a little dilute sulphuric acid, which also 
aids the separation of the phenol from the aqueous solution. 
The sodium sulphate solution is carefully and completely drawn 
off. The crude phenol thus obtained contains from 20 to 25 per 
cent water and tar. These are removed by distillation in a still 
similar to a tar still, although much smaller. The dry, crude 
phenol is fractioned in column stills heated by direct fire or super- 
heated steam, but otherwise the stills are similar to those used 
for benzols. These yield, first, a crystallizable phenol, second, 
a fraction not sufficiently rich in phenol to crystallize, and a third 
fraction containing principally cresols. The fractioning of the 
crude phenols is conducted at reduced pressure at some works. 
By this process, owing to the low temperature of the distillation, 
a larger yield of phenol is obtained. 

The crystallizable fraction is further purified by repeated 
crystallization with the aid of refrigeration and with the addition 



COAL TAR AND ITS DISTILLATION PRODUCTS 257 

in the last crystallization of water to dilute the cresols present. 
Finally, these purified crystals are redistilled, condensed in block- 
tin worms and collected in tin receivers so arranged that they can 
be heated to melt the phenol in order that it may run in a liquid 
state into containers. 

A properly purified phenol will remain white for more than 
a year, showing no trace of the red color commonly seen in crystal 
carbolic acid. 

The second portion of the alkaline liquor from the treatment 
of the dead oil, containing largely cresylate of soda, is saturated 
with carbonic and sulphuric acids in the same manner as is the 
portion rich in phenol. It is not customary to boil the cresylate 
of soda to remove the oils and pyridine bases unless it is desired 
to make pure cresol. The crude cresol is freed from tar and water 
by distillation and is then marketable as 95 to 100 per cent cresylic 
acid. 

PHENOL, carbolic acid, hydroxy-benzene, CeHsOH, w T hen 
pure, is a white, crystalline mass, with sp.gr. 1.084 at 0° C, 
melting at 42° C., boiling at 182° C, having a characteristic 
odor and when very dilute a sweetish taste. 

It is soluble in all proportions in alcohol, ether, chloroform, 
glacial acetic acid and glycerine. It liquefies on the addition 
of 14 to 15 per cent of water, and thus becomes the No. 4 car- 
bolic acid of commerce. It dissolves in about 20 parts of water 
at 25° C. It is a corrosive and irritant poison. Undiluted 
alcohol is one of the best washes for phenol burns. Carbolic 
acid is largely used in medicine and surgery as an antiseptic 
and disinfectant and in the arts in the manufacture of dyes. 
It is employed in the manufacture of picric acid, trinitrophenol, 
which finds a large use in the manufacture of high explosives, 
and is also used as a yellow dye. 

CRESOL, cresylic acid, hydroxytoluene, C6H4CH3OH, is a 
mixture of three isomers, has a sp.gr. of 1.032 to 1.038 at 25° 
C, and distills between 190 and 205° C. It is used as an anti- 
septic and disinfectant and is much less corrosive than phenol 
and is a more efficient antiseptic. 

The three isomers composing cresol have the following prop- 
erties : 

ORTHOCRESOL, orthocresylic acid, ortho-oxy-toluene, ortho- 
methylphenol, CefeOHXCHs), with the CH3 and OH groups 
in the (1-2) position, is a white crystalline substance melting 
at 28 to 30° C, into a colorless liquid and boiling at 187 to 



258 ELEMENTS OF INDUSTRIAL CHEMISTEY 

189° C. It is soluble in thirty parts of water, in alcohol, ether, 
chloroform, and the caustic alkalies. 

METACRESOL, metacresylic acid, meta-oxy-toluene, meta- 
methylphenol, has the CH3 and OH groups in the (1-3) position 
and is a colorless liquid, sp.gr. 1.0498 to 1.05 at 0° C. It boils 
at 202° C, is soluble in alcohol, ether, chloroform, the caustic 
alkalies, and slightly in water. 

PARACRESOL, paracresylic acid, para-oxy-toluene, parameth- 
ylphenol, with the CH3 and OH groups placed in the (1-4) 
position, is a white crystalline mass, melting at 36° C, and 
boiling at 198° C. It is soluble in alcohol, ether, chloroform, 
caustic alkalies, and slightly in water. 

XYLENOL, di-methyl-phenol, hydroxj^-xylene. The six possi- 
ble isomers are probably present in the fraction of crude cresylic 
acid boiling between 210 and 230° C. and which has a sp.gr. 
between 1.02 and 1.03 at 15° C. They are on the whole con- 
siderably more soluble in water and less corrosive than the 
cresols. They are principally used in disinfectants of the " cre- 
olin " type on account of their high phenol coefficient, which is 
between ten and twelve. They are not generally separated 
from the cresylic acid except when pure cresols are made. 

NAPHTHALENE. The heavy oil fraction, if the removal of 
the naphthalene is desired, is run into shallow tanks or pans, 
either from the still or after the tar acids have been extracted 
and allowed to become cold, when the larger part of the naph- 
thalene crystallizes. The oil is drawn off and the crystals are 
either shoveled into piles to drain, or are passed through a 
centrifugal which leaves the crystals nearly dry and in com- 
dition for market as " drained creosote salts " or crude naph- 
thalene. 

Refining naphthalene consists in freeing it from adhering 
heavy oil and from unsaturated, easily oxidized compounds. 
The crude material should be in a coarse crystalline condition 
to allow of the proper extraction of the oil. If it is in a slimy 
state it should be recrystal'lized. The crystals are either washed 
with hot water in centrifugals, which removes the larger part 
of the adhering oil, or they are hot pressed in hydraulic presses. 
The latter process is more expensive and less efficient than the 
former. After this operation the naphthalene should have a 
melting-point of not less than 76° C., and will still contain 
from 4 to 6 per cent of oils. The partly purified naphthalene 
is now distilled, to remove the tarry bodies that have been 



COAL TAR AND ITS DISTILLATION PRODUCTS 259 

carried forward from the original tar. This process is conducted 
in plain, externally fired iron stills, similar to tar stills, but with 
lead worms. The distillate is kept in a melted state and run 
into lead-lined agitators similar to those used for benzols, and 
washed with sulphuric acid, 1.835 sp.gr., several waters, and finally 
with caustic soda solution, of about 1.16 sp.gr. Great care must 
be taken to remove as much as possible of the acid before the first 
water is added, so as to prevent the tarry polymerization products 
from being redissolved by the naphthalene. The soda solution 
is drawn off completely, as small amounts of soda will cause 
the bottom of the still to be rapidly burned out. It is neces- 
sary to reject the first portion " heads," and the last portion, 
" tails," of the distillate from the final distillation of refined 
naphthalene, as the " heads " are discolored by the washings 
of the worm and with water containing dissolved bases, metallic 



u u u u u — o — d — cm — n — cm — n — cm a 
n n n n n n n n n n n 




L U U 11 U II UU — lLUUiiUUiiUU 

Fig. 89. 



salts, etc., while the oils are concentrated in the " tails." The 
sum of the rejected portions should not exceed J to 1 per cent 
of the distillate. 

The water- white refined naphthalene is run into shallow pans 
to cool, when it can be broken up and sold as lump, or is run 
Into copper tanks heated by steam, from which it is available for 
casting into balls, etc., or for use in the subliming pans. Sub- 
liming pans, Fig. 89, are large shallow iron tanks heated by steam 
and connected by an iron hood with a smoothly sheathed room 
in which the sublimed vapors condense in transparent plates, 
" flake naphthalene." About 150° C. seems to be the most 
satisfactory temperature in the subliming pans. A higher tem- 
perature can be economically employed in winter and a some- 
what lower one in summer. Naphthalene, CioHs, is a solid 
hydrocarbon at ordinary temperatures, melting at 79-80° C, 
and boiling at 218° C. Its specific gravity in the solid state 



260 ELEMENTS OF INDUSTRIAL CHEMISTRY 

is 1.151 at 15° C. and in the liquid state is 0.9778 at 80° C. 
It volatilizes at ordinary temperatures and very readily on the 
steam bath. It crystallizes in transparent rhombic plates, which 
are slightly soluble in hot but insoluble in cold water. It is 
very soluble in chloroform, benzene, ether, alcohol, methyl 
alcohol and paraffine. 

The purity of refined naphthalene is indicated by the faint 
purple or pink tint when a lump is dissolved in hot concentrated 
sulphuric acid. If the acid is turned a deep red the sample is 
likely to become discolored on standing. Naphthalene is used 
as the starting-point of several classes of colors, including nearly 
all of the azo-colors and for artificial indigo, in candles, cellu- 
loid, as a substitute for camphor to prevent moths in woolens, 
and to some small extent as a gas enricher in lights of the albo- 
carbon type. It readily nitrates directly to mononitro naph- 
thalene, which crystallizes in yellow needles, with sp.gr. 1.331 
at 4° C, melting at 56° C, and boiling at 304° C. It is easily 
soluble in alcohol and petroleum oils. Its principal uses are 
the manufacture of certain smokeless powders and to remove 
the fluorescence from petroleum oils, for which latter purpose 
from 2 to 3 per cent is used. 

ANTHRACENE. This oil is the portion of the distillate from 
coal tar which vaporizes above 270° C. At this temperature a 
cut should be made if the distillation is carried to hard pitch. 
This oil boils between 250 and 400° C, and has a specific gravity 
of nearly 1.1. Its color is yellowish-green when first made, 
but it darkens to almost black. It contains besides anthracene, 
naphthalene, methylnaphthalene, pyrene, acridene, phenanthra- 
cene, fluorene, etc., all of which are solids, except methylnaph- 
thalene, and a mixture of oils of which we know very little. 

The anthracene fraction is run into shallow tanks and the 
solid compounds separate out on cooling. This process requires 
from one to two weeks. 

Refrigeration has been tried to shorten the time, but it makes 
the oils more viscid and the separated crude anthracene much 
more impure. The semi-solid mass is transferred to bag filters 
or to a filter press and as much as possible of the oil driven out 
by compressed air. The nearly dry cakes from the bags or 
filter press, containing about 10 to 15 per cent anthracene, are 
subjected to a pressure of from 50,000 to 70,000 lbs. in hydraulic 
presses so arranged that they may be kept hot by steam coils 
or steam-heated plates. This treatment brings the anthracene 



COAL TAE AND ITS DISTILLATION PRODUCTS 261 

content to from 25 to 35 per cent. These press-cakes are ground 
and purified by washing in a closed agitator with hot solvent 
naphtha from the fight oil. 

Lower boiling benzols have been used for this purpose, but 
they dissolve the anthracene itself. The whole charge, when 
thoroughly mixed, which may require several hours, is run into 
a closed filter and the solvent removed by compressed air. 
P;yridme bases are said to be a better solvent for the anthracene 
impurities than solvent naphtha and is said to yield 80 per 
cent anthracene, while 70 to 75 per cent is the limit with solvent 
naphtha. 

A somewhat more pure anthracene is produced by the sub- 
limation of the washed material. The subliming pans are similar 
to those used for naphthalene except that they are heated by fire 
and have jets of superheated steam impinging upon the surface 
of the melted anthracene. The vapors are condensed by water 
jets. The oil from the first crystallization of the crude anthracene 
is distilled in a clean still till crystals appear upon cooling the 
distillate, when the residue containing the anthracene is run into 
pans and t reated the same as the original fraction. 

When the oil will jdeld no more anthracene it is used to soften, 
" cut back," pitch, as " Carbolineum Avenarius," for the treat- 
ment of timber, and mixed with the creosote oil. 

Anthracene, C14H10, was discovered by Dumas and Laurent 
in 1832 and recognized as a characteristic constituent of coal tar 
by Fritzsche in 1867. It boils at 363° C, melts at 213° C, and 
has a specific gravity of 1.147 at 15° C. It crystallizes, when 
pure, in white or yellow rhombic plates with a blue fluorescence. 
It is soluble in benzene, ether, chloroform, carbon bisulphide, 
and in hot alcohol, but only sparingly soluble in cold alcohol. 

It is slowly converted by sunlight into paranthracene. It is 
of great importance commercially as the starting-point for the 
synthetical alizarines, 



CHAPTER XII 
THE PETROLEUM INDUSTRY 

ORIGIN OF PETROLEUM. The origin of petroleum has been 
the subject of much discussion among scientists throughout the 
world, the theories set forth being divided into two groups, 
the inorganic and the organic. The inorganic theories consider 
petroleum to have been produced by the reaction of inorganic 
substances. Berthelot believed it to have been formed by the 
action of steam and carbon dioxide on highly heated alkali 
metals, which, according to DaubreVs hypothesis, were supposed 
to exist in the depths of the earth. Mendeleeff believed it to 
have been formed by the action of water on highly heated metallic 
carbides. These theories have been supported by laboratory 
experiments, yet they are not in accord with the geological con- 
ditions under which petroleum is found. 

The organic theories that petroleum has resulted from the 
decomposition of either animal or vegetable matter, or both, 
comply more fully with the views held by the geologists, and have 
also been supported by laboratory experiments. Peckham 
believed that petroleum was produced by the slow distillation 
of animal and vegetable matter at a low temperature; Phillips 
and Sterry Hunt, that it was due to the decomposition of vege- 
table matter under water and in the absence of air. Orton con- 
sidered Pennsylvania petroleum to have been derived from organic 
matter of bituminous shale, probably vegetable; and Canadian 
oil produced from limestone, probably animal. 

CONSTITUTION. Crude petroleum consists essentially of a 
complex mixture of hydrocarbons of different boiling-points, 
often accompanied by small percentages of oxygen, sulphur, and 
nitrogen compounds. The oils produced from different localities 
often vary widely in chemical composition, but they are all 
refined by the same general methods. 

The oil refiner divides petroleum into two general classes, 
viz., the " parafnne-base," those yielding solid hydrocarbons of 
the paramne series CnH2n+2; and the "asphaltic," or those rich 

262 



THE PETROLEUM INDUSTRY 263 

in asphalt and containing practically no solid paraffines. There 
is, however, no sharp line of distinction, as some of the oils from 
Kansas, Oklahoma, Northern Texas, and Illinois contain both 
asphalt and paraffine. 

LOCALITY. The oil from Pennsylvania, of the Appalachian 
field, which includes Pennsylvania, New York, southeastern 
Ohio, West Virginia, and Kentucky, is generally considered the 
best grade of petroleum produced in large quantities. This is 
a " paraffine-base " oil, but contains small quantities of the olefin 
series, C2H2H, the benzene series, C n H2n-6, and traces of the 
naphthene series, which are hydrogen addition products of the 
benzene series, and isomeric with the olefin series. The color by 
transmitted light varies from amber to red, and by reflected 
light is green, due to the so-called " bloom " or fluorescence. 
In specific gravity it ranges generally from .8641 to .7821 (32.0 
to 49.0° Beaume). It contains very little sulphur (.06 to .084), 
practically no asphaltic matter, and gives a good yield of gaso- 
line, illuminating oils, and paraffine wax. 

The Canadian oil and that from Lima, Ohio, are also paraffine- 
base oils; but as they are high in sulphur (Lima oil, 0.6 per cent, 
and Petrolia, Canada, 0.98 per cent), the illuminating oils sepa- 
rated from them have to be desulphurized in order to make them 
merchantable. 

The petroleum from Illinois is lower in sulphur (.25 per cent 
to .32 per cent), much of it being refined without special treat- 
ment; but that from some pools contains asphalt as well as solid 
paraffine, as do some from Kansas, Oklahoma, and Northern 
Texas. 

The California oils are of the asphaltic type and are made up 
of a large proportion of nitrogen bases of the pyridin, or hydro- 
pyridian, and chinolin type. They also contain members of the 
terpene series, C n H2n-4, and the benzene series, C n H2 n -6, as does 
the oil from Beaumont, Texas. 

There are small quantities of petroleum produced in Penn- 
sylvania, West Virginia, and other localities, which possess 
lubricating qualities in their natural state, and need only to be 
strained before they are placed on the market; but, as the pro- 
duction is small, these oils are only of passing interest. 

Of the other countries, Russia is the largest producer. The 
oil from Baku differs chemically from the Pennsylvania oil in 
being made up largely of the " naphthene " series, which, accord- 
ing to Markownikow and Ogloblin, constitutes 80 per cent. 



264 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



Smaller fields exist in Sumatra, Java, Borneo, Galicia, Rou- 
mania, Egypt, Persia, Africa, India, Japan, Mexico, Germany, 
Peru, and Italy. 

PRODUCTION. Crude petroleum is obtained by drilling through 
the overlying strata to the oil-producing sands beneath, proceed- 
ing in practically the same manner as in boring an artesian- 
water well. The depth of the wells depends on the locality. 
In Pennsylvania the depth varies from 300 to 3700 ft. It some- 
times happens in drilling, when the oil-bearing stratum is tapped, 
that the oil rushes out of the well with great force, due to confined 
gas; such a well is called a " gusher." Some of the big gushing 
wells of Russia have started producing at the rate of 200,000 
barrels of oil per day. The famous Lucas well struck at Spindle 
Top near Beaumont, Texas, on Jan. 10, 1901, at a depth of from 




Fig. 90. 



1029 to 1069 ft., is estimated to have started gushing at the rate 
of 70,000 barrels per day, and probably flowed 500,000 barrels 
before it could be tapped. 

Petroleum is transported great distances from the fields to 
the storage tanks (30,000 to 75,000 barrels capacity) of large 
refineries, through pipe lines of from 4 ins. to 8 ins. in diameter, 
the average line being 6 ins. The longest distance is from the 
Oklahoma field, via Kansas City and Chicago, to the seaboard 
a distance of about 1600 miles. 

REFINING. The first step in the separation of petroleum 
into its various products is fractional distillation, and this is 
modified according to the nature of the crude oil, and the prod- 
ucts desired. The horizontal steel stills used for this operation 
vary in construction, but those in general use in this country 
are cylindrical steel shells set in brickwork, as shown in Figs. 
90 and 91, the upper half being exposed except for an iron jacket 



THE PETROLEUM INDUSTRY 



265 



covering. The largest stills of this type are about 42 ft. long 
by 15 ft. in diameter, with a charging capacity of about 1200 
(42 gallons) barrels. They may be either end or side fired, the 
latter being preferable on account of the ease with which the 
still can be controlled. The fuel used may be either coal or 
oil, it being cheaper to burn oil in some cases, as in California 




Fig. 91. 



and Russia, where, owing to the scarcity of coal, oil is used 
almost entirely. 

The stills are usually fitted with domes at the top which are 
con ected with 12- to 16-inch vapor pipes, or " goose necks " 
that lead to condensers. The condensers consist of coils of pipe 
set in tanks, through which cold water is circulated. The pipes 
connecting the condenser coils with the "tail house/' some dis- 
tance away, are called the " running lines," and are usually pro- 
vided with traps for separating the uncondensed gas which is 
subjected to pressure in order to separate the light gravity gas- 
oline carried by it. The residual gas is utilized in gas engines 



266 ELEMENTS OF INDUSTRIAL CHEMISTRY 

or burned under the stills. The running lines are intercepted 
in the " tail house " by " look boxes " enclosed with glass, so that 
the " stream " (distillate flowing from the condenser) can be 
watched by the stillman in charge. 

The method of distilling is dependent on the products desired. 
When petroleum is distilled by means of fire alone, the heavy 
vapors which condense in the top of the still drop back into the 
superheated oil, and are thereby partially decomposed. This de- 
/ composition, or " cracking," causes oils of lower specific gravity 
than are normally present to be produced, and is called the 
" dry," or destructive distillation. This method is used when** 
large percentage of burning oils is -desired. The products when 
running on Pennsylvani^or parafnne-base crude oil, are: naph- 
tha (sometimes redistilled, for cymogene, rhigolene, petroleum 
spirit and gasolene), burning oils, gas and fuel oils, paraffine 
lubricating oils, wax and coke. Heretofore the practice has been 
first to " run " the " crude " to tar (about 9 to 12 per cent resid- 
uum) in the crude stills, and to distill the tar separately at the 
tar stills for paraffine or " tar " distillate (lubricating oil distillate 
containing the paraffine wax) and coke. 

The latest practice is to continue the distillation to coke in 
" tower stills " without interruption and separate the different 
raw products in one distillation. The " tower still "is so called 
on account of the tower-like aerial condensers connecting with 
the goose-neck, and interposed between the stills and water- 
cooled condensers. The office of these towers is one of fractional 
condensation. 

They usually consist of a top and bottom gas chamber con- 
nected by pipes, around which the air circulates, causing partial 
condensation. The vapor pipe or goose-neck carrying the hot 
vapors from the stills connects into the bottom gas chamber of 
the first tower and travels up through the pipes through the 
top gas chamber into the bottom of the second tower, and so on 
through the series to an ordinary water-cooled condenser, con- 
sisting of coils of pipes set in a tank of water. The towers and 
water condenser all connect in the receiving house (tail house) 
with " lookboxes," enclosed with glass so that the flow of the 
different streams may be observed and samples can be taken for 
gravity tests. 

The tower still has many advantages over the old style appara- 
tus. Condensation taking place in each tower separates what 
would otherwise be one product into as many products as there 



(F) 

Tar Distillate (30°BJ 

Cooled artificially and filter 

pressed at 20 to 24°P. 



etroleum S] 
(58^76°Beaur 



Acid 



Wax Tailings 



Coke 



1 



Slack Wax 
(95/l05°F.M.PJ 
Containing 30-40$ Oil 
Sweated 



_Poots 




Soft Wax 
Re-Sweated 



Hard Wax 

Washed with Naphtha, filter 
pressed. Naphtha distilled 
off and Wax filtered through 
Bone Black or Fullers Earth 



Soft Wax 
(almost free from oiD 
filtered through Bone Black 
or Fullers Earth 



Refined Paraffine Wax 



White Scale Wax 



SI. 



DiA 



[To face page 266.] 



Pennsylvania Onide Petroleum 



.:■! ■■;:■ 



*— «"*-* 








— . 




Petroleum Spirit 





Low Test Burnl 
Light Naphtha 8t<1( . t 






"skX°Sv"w 



Uiagkam Showing Products Obtatned ekom Pennsylvanza Chude taw™ «■ ■JSSST*'' 
Prepared by T. T. Gray for Rogers and Auberfs "Industrial Chemistry" and Rogers' Elements of Industrial Chemistry. 



THE PETROLEUM INDUSTRY 267 

are towers, and therefore reduces further necessary redistilla- 
tion to a minimum. 

When lubricating oils of superior quality, such as spindle 
and cylinder oils, are being manufactured, it is necessary to 
prevent the decomposition of the crude oil as much as possible. 
This is accomplished by introducing steam (dry but not neces- 
sarily superheated) into the oil in the still by means of a perfo- 
rated coil. The atmospheric«pressure upon the mixture is divided 
between the hydrocarbons and the steam and the partial pressure 
on the hydrocarbons is less than the atmospheric pressure, 
consequently they disti.l over at temperatures lower than their 
normal boiling-points. The sfeam jets also keep the oil in con- 
stant state i of agitation, thereby preventing it from getting 
overheated at the bottom of the still next to the fire. This 
method is called the " steam " distillation; the products are: 
Naphtha, burning oils (less than when distilled destructively), 
gas and fuel oils, spindle oils, paramne wax and cylinder oils. 
Some refiners use the vacuum distillation, in conjunction with 
the steam distillation, where, by the aid of a pump, a partial 
vacuum is created in the still, and the hydrocarbons pass over 
at temperatures much below their normal boiling-points. The 
vacuum stills are of the same general type as the ordinary hori- 
zontal " crude stills, " but are smaller and heavier. 

Naphtha and Illuminating Oils. The chart on opposite 
page shows the different steps in the " dry " distillation of Penn- 
sylvania crude oil. The " stream " (distillate flowing from the 
condenser) begins running into the " tail house " under ordinary 
conditions at about 80° Be. (.6666 sp.gr.) ; it is practically water 
white in color, and is " run ,; into light naphtha (Fraction A) 
until it reaches 69° Be. (.6965 sp.gr.). From 69 to 58° Be. 
(.7035 to .7446 sp.gr.) the distillate is collected as heavy naphtha 
(Fraction B); but as it is more or less contaminated with 
some of the heavier hydrocarbons of boiling-points too high 
for use as naphtha, it has to be redistilled in a (( steam still " 
(a still heated by steam coils and steam jets). The upper 
fraction is added to the light naphtha (Fraction A), and the 
residue used for blending with the low-test burning oil which 
follows. 

The naphtha Fractions A and B, representing from 12 to 15 
per cent of the crude oil, can be worked up in several different 
ways. They can be used for all ordinary purposes without 
further refining, or may be redistilled, the very volatile fractions 



268 



ELEMENTS OF INDUSTRIAL CHEMISTRY 




being condensed by extreme cold, and under pressure, thereby- 
separating cymogene, rhigolene, gasolene. 

In order to improve the odor of the naphtha it is sometimes 
treated with about 2 to 4 lbs. of 66° Be. commercial sulphuric 

acid per barrel of 50 gallons, by 
agitation in tall, lead-lined cone- 
bottomed tanks, Fig. 92, called 
agitators, of from 300 to 500 bar- 
rels' capacity, provided with me- 
chanical stirring gears, in prefer- 
ence to an air blast, in order to 
prevent loss by evaporation. The 
acid is allowed to settle and draw 
off into the sludge-acid tank. The 
naphtha is washed thoroughly with 
water by means of a spray and 
finally by agitation with water, 
and is then made alkaline with 
caustic soda of 4 to 10° Be., and 
finally washed with w r ater until 
neutral, when it is pumped into 
tanks and allowed to settle until 
bright. After this treatment it becomes known as " deodorized 
naphtha." 

To recur to the original distillation, from 58 to 43° (.7446 to 
.8092 sp.gr.), or as long as the stream runs good color (almost 
colorless) the high -test burning oil (Fraction C), is collected. 
It is " steam stilled " to 150° F. fire test, and the distillate 
put into heavy naphtha (Fraction B). The residue from the 
steam, still known as 150° W. W. Stock, is treated as described 
later. 

When the distillate begins to go " off color," due to cracking, 
it is " cut into " low -flash burning oil distillate (Fraction D), 
which is also steam stilled, ,the volatile fraction being naphtha 
of 70° Be. (.7000 sp.gr.), called " gas naphtha " from its objec- 
tionable odor. Gas naphtha contains a large proportion of 
unsaturated hydrocarbons, and goes into the cheaper grades 
of naphtha. The appearance of so low a specific gravity fraction 
at this stage of the distillation illustrates clearly the effect of 
the " cracking ". process. 

The burning oil stocks from the steam stills, consttutitin 
from 65 to 75 per cent of the crude oil charged, are treated ag 



Fig. 92. 



THE PETROLEUM INDUSTRY 269 

the rate of 5 to 10 lbs. of 66° commercial sulphuric acid per 
barrel, in order to improve the color and odor, also to remove 
decomposition products which cause the flame to smoke when 
burned in lamps. The process is performed in agitators in much 
the same manner as with naphtha, only an air blast is used for 
agitation instead of a stirring gear. In order to get the full 
benefit of the acid, any water present must first be drawn off, 
and a small amount of acid added in order to remove all of the 
remaining water; this is agitated for from twenty to forty 
minutes, allowed to settle from the oil and then drawn off. 
The remaining acid is then added and the mass agitated for 
from one-half to one hour, allowed to settle from three to five 
hours, and drawn off. The acid treatment removes the tarry 
matter formed during distillation, also a large percentage of 
the unsaturated hydrocarbons and sulphur compounds. The 
acid is turned almost black after treatment, and is known as 
" sludge " acid. The " sludge " acid is allowed to settle from 
the oil and is then drawn off into tanks and delivered to the 
acid-separating plant for the recovery of the acid. After the 
separation of the sludge, the oil is washed thoroughly with 
water, made alkaline with caustic soda of from 4 to 10° Be. 
by agitation, and then washed with water until neutral; the 
wash water is separated and the oil pumped into settling 
tanks where it is allowed to settle until bright. 

SULPHUR CONTENT. Pennsylvania petroleum contains very 
little sulphur (.06 to .082 per cent), the burning oils made fiom 
it therefore requiring no further treatment; but when oils con- 
taining considerable sulphur, such as that from Lima, Ohio, 
Texas, and Canada, are being refined, a special desulphurizing 
is necessary in order to get rid of most of the sulphur compounds, 
which cause charring of the lamp wick, and burn with a smoky 
flame. There are many processes for affecting this, the two 
best known being the " litharge " and the " Frasch " methods. 

The litharge method consists of agitating the oil with a 
solution of litharge (lead oxide) in caustic soda; the sulphur 
is precipitated as a lead sulphide and drawn off. Although this 
method reduces the sulphur considerably, it is not as thorough 
as the " Frasch " process, where the oil is heated with finely 
divided copper, or copper oxide in " sweetening " stills provided 
with heavy stirring gears. The copper sulphide formed is after- 
wards roasted in order to remove the sulphur and the resulting 
copper oxide used for the next treatment. 



270 ELEMENTS OF INDUSTRIAL CHEMISTRY 

LUBRICATING OILS. The residue (E) from the original 
distillation of the crude oil (10 to 12 per cent) is known as tar. 
It is from 21 to 22° Be., very dark in color and contains the 
paraffine lubricating oil and wax. 

In order to manufacture the lubricating oils known in the 
trade as " paraffine oils," the tar is first distilled destructively 
in stills of practically the same type as the " crude stills," only 
they are smaller in capacity (250 to 500 barrels). The process 
is continued until everything has passed over except the coke 
formed by the destructive distillation. At the latter part of 
the distillation, just before the still has " coked," a yellow, 
sticky, semi-asphaltic product passes over, which is known as 
" wax tailings"; on analysis this has been found to contain 
anthracene, chrysene, and other products formed by the " crack- 
ing " process. The bottoms of the stills often get red hot during 
the coking period. The coke resembles gas coke in appeara^ ce, 
but is more fragile. The yield from tar averages from 10 to 
12 per cent, or about 1 per cent from the crude oil, and on 
account of its purity is used principally for making electric 
light and battery carbons, and also to some extent in metallur- 
gical processes. 

The distillate from tar, known as paraffine, or impressed tar 
distillate (Fraction F) is yellow in color and contains the wax 
and paraffine lubricating oils. It has a gravity of 30° Be. (.875 
sp.gr.), and a solidifying point of about 70° F. due to the solid 
paraffines present. It is treated with 66° Be. commercial sul- 
phuric acid at the rate of 8 to 10 lbs. per barrel in the same 
manner as the treating of burning oils, the agitator in this case 
being heated by a steam jacket in order to keep the paraffine 
distillate liquid. After treatment it is delivered to the pressing 
plant, where it is chilled down to from 20 to 24° F. in steel 
shells containing stirring gears called " coolers " provided with 
jackets through which cold brine is circulated. A refrigerating 
plant is therefore necessary when refining crude oils containing 
solid paraffines. When the proper temperature (20 to 24° F.) 
is reached, it is pumped to a filter press, Fig. 93, which is pro- 
vided with plates covered with canvas; the oil passes through 
and drains off, and the wax is held by the canvas. The oil 
thus expressed is known as pressed tar distillate (Fraction G), 
and the wax separated, containing considerable oil (30 to 40 
per cent), known as " slack wax," is removed from the canvas- 
covered plates, by scraping with " spuds," when it is carried 



THE PETROLEUM INDUSTRY 



271 



by means of conveyors under the press to the " slack-wax " 
tank. 

The pressed-tar distillate has a cold test (solidifying point) of 
20 to 25° F., and is used for making all of the paramne lubri- 
cating oils. It is charged into the ik reducing stills/' which are 
the same type as the crude stills, but smaller in capacity (about 
300 to 500 barrels); and the upper halves, instead of being ex- 
posed, are bricked in. Here it is " steam reduced " according 




Fig. 93. 



to the test desired, by firing underneath and at the same time 
introducing steam into the body of the oil by means of a per- 
forated coil placed inside on the bottom of the still. In making 
high-viscosity oils the distillation would naturally be carried 
farther than when making low-viscosity oils — as the viscosity 
increases with the boiling-point in the same homologous series 
of hydrocarbons. The first fraction, separated at 36° Be. 
(.8433 sp.gr.), is put into the low -test burning oil fraction; the 
second fraction down to 32.5 Be. (.8615 sp.gr.), being too high 



272 



ELEMENTS OF INDUSTEIAL CHEMISTRY 



in specific gravity for burning oils, and having practically no 
value as lubricating oil, is separated for " fuel oil." The third 
fraction, cut at 28° Be. (.886 sp.gr.), is used for making low- 
viscosity lubricating oils, as described by chart, and the fourth 
for medium lubricating oils. The residue, which is heavy lubri- 
cating oil stock of dark color, is pumped out of the still through 
a coil of cast-iron pipe set in water called a cooler, in order to 
prevent oxidation when exposed to the air. The cool oil is treated 
with from 20 to 50 lbs. of commercial 66° Be. su'phuric a id 
per barrel in an agitator of from 200 to 1000 barrels' capacity 
in the same manner as described under burning oils, except that 
the agitation is kept on longer — one to two hours — and it takes 
longer for the sludge acid to settle — four to six hours. 

After drawing off the sludge, the oil is transferred to a " lye " 
agitator, where most of the remaining acid is washed out by 
agitation with water. It is then agitated with caustic soda 
of from 1 to 6° Be. until a distinct alkaline reaction with phenol- 
phthalein is obtained. The " lye " containing s ilpho-com- 
pounds, formed by the acid treatment, is drawn off, and the 

oil washed well again with water, 
and finally with hot water, until 
a neutral reaction is obtained. 
The water is separated and the 
oil transferred to shallow tanks, 
where it is warmed to 150 to 
160° F. by closed steam coils, 
and air blown up through it 
from a perforated coil until all 
the moisture is removed, leaving 
the oil clear and bright and 
ready for the market. 

PARAFFINE WAX. The slack 
wax expressed from the tar dis- 
tillate usually contains from 30 
to 40 per cent of oil, which is 
gotten rid of by one of the fol 
lowing methods : it may be mixed 
with naphtha and cooled until the wax crystallizes out, and then 
refilter pressed; or it may be removed by the process known as 
sweating. The " sweaters " consist of tiers of pans arranged in 
rooms, as shown in Fig. 94, the rooms are heated by steam coils, 
each room being known as an oven. The pans are first filled 



ay 




Fig. 94. 



THE PETROLEUM INDUSTRY 273 

with water to the level of a wire screen at A and the melted wax 
is charged in until the pans are full, after which cold water is 
circulated through coil B until the wax solidifies. The water is 
then drawn off from underneath the solid cakes of wax by valve 
C and warm water circulated through coil B and the rooms also 
heated by steam coils. The heat causes the oil to sweat out of 
the wax, and it drains off and runs into a tank. Tne oil, or 
" foots," thus separated, containing some soft wax, is filter pressed 
and worked up the same as the unpressed tar distillate. The 
sweated wax remaining in the pans is melted, drawn off, and 
delivered to the filtering plant, where it passes through bone 
black or fuller's earth contained in long cylindrical tanks called 
filters in rooms heated from 130 to 180° F. This operation 
removes practically all of the color. It is then molded into cakes 
either in pans or between hollow plates cooled by the circulation 
of water in apparatus known as the " Gray Wax Caking Machine." 

THE STEAM DISTILLATION. Spindle Oils and Cylinder Stocks. 
In making special high-grade lubricating oils, the distillation of 
the crude oil is carried on in the same manner as the destructive 
distillation until just before the " cracking " point is reached, 
when steam is introduced as before mentioned; by this method 
decomposition is practically prevented. The yield of burning 
oil is therefore much lower and lubricating oil much higher. The 
distillation is carried on until about 15 to 18 per cent remains in 
the still. The reduced stock, known as steam-refined cylinder 
stock, is pumped out through a cooler. 

The steam-refined cylinder stocks are sometimes further 
refined by filtration through bone black or fuller's earth and are 
then known as filtered cylinder oils. Cylinder oils are recognized 
by their high flash point and viscosity. 

After the burning oil fraction has been separated, the rest of 
the distillate, passing over during the distillation, is called "spindle 
distillate." It contains considerable wax, which is removed by 
filter pressing in exactly the same manner as with the unpressed 
tar distillated. The pressed spindle distillate is reduced in the 
same manner as the paraffine oils, except that the reduced spindle- 
oil stock, instead of being treated with acid, is filtered through 
bone black, or fuller's earth, contained in cylindrical filters of 
about 15 to 20 tons' capacity. The fuller's earth removes the 
asphaltic matter, and improves the color of the oil. The first 
oil running through the filter is almost colorless; but as the 
fuller's earth " adsorbs " the asphaltic matter, it soon loses in 



274 ELEMENTS OF INDUSTRIAL CHEMISTRY 

decolorizing value and the oil runs darker until it reaches a point 
where it is not practical to filter any longer, when the operation 
is stopped. The oil held by the fuller's earth is washed out by 
allowing naphtha to filter through it, and the naphtha remaining 
in the filter is collected by steaming it out with an open steam jet, 
and running it through a condenser. The oil washed out by the 
naphtha is separated by distillation, and the fuller's earth is 
heated in a retort nearly to redness in order to dry it and burn 
off the asphaltic matter, when it is used over again. 

Vaseline and " petrolatum " are reduced stocks made from 
selected crude oil by careful reduction and subsequent filtration 
through fuller's earth, or bone black. 

Asphaltic Base Crude Petroleum. The refining of 

asphaltic base crude oil is substantially the same as described in 
the preceding methods, excepting the residue, which, instead of 
being tar, or cylinder stock, is asphalt. The burning oils are not 
of such good quality, a larger percentage of fuel oil is obtained, 
and the lubricating oils are of higher specific gravity and lower 
flash than those made from the paraffine-base petroleum. | 

SHALE OIL. In Scotland, and to a small extent in other 
countries, paraffine oils are obtained by the destructive distillation 
of bituminous shale. The formation of the oil is dependent on 
the decomposition of the organic matter present. 

Shale varies in color from dark gray to almost black, the 
products obtained being ammonia water (separated as a sulphate) , 
paraffine wax, paraffine oils, burning oils, and phenols. The shale 
is first reduced to very small pieces, and then distilled contin- 
uously in circular vertical retorts, by charging in the top through 
a hopper, and drawing the exhausted shale out at the bottom. 
Steam is usually introduced into the retort. The vapors pass 
through a condenser, and the crude shale oil and ammonia liquor 
are separated. The crude shale oil is dark in color, ranging in 
specific gravity from .86 to .89, and having a cold test of 90° 
F., due to solid paraffines. It is distilled by either the intermit- 
tent or continuous process to coke in practically the same man- 
ner as with the tar from crude petroleum, except that steam 
is introduced through perforated coils during the distillation 
process. The treatment of the various fractions, i.e., naphtha, 
burning oil, paraffine distillate (containing the paraffine wax) — 
consists of a treatment with sulphuric acid and alkali in the same 
manner as with petroleum; the alkali in this case, in addition to 
neutralizing the acid, removes the phenols which have been 



THE PETROLEUM INDUSTRY 275 

formed during the first distillation. The phenols are liberated 
from the waste " lye " by passing carbon dioxide through it. 

OZOKERITE. Ozokerite, or earth wax, is, as the name implies, 
a wax-like substance found in small quantities throughout the 
world, usually associated with rock salt or gypsum. The prin- 
cipal deposit occurs in the neighborhood of Boryslaw, in Galicia. 
It consists largely of solid paraffine hydrocarbons, and is supposed 
to have resulted from the evaporation and decomposition of crude 
petroleum. Like petroleum, it is found in different ages, but 
principally in the Tertiary and the Cretaceous. The appearance 
and physical character vary, some grades being soft and others 
brittle, and the color ranges from yellow to black. The specific 
gravity averages from .85 to .89 and the melting-point from 
130 to 156° C. The Galician ozokerite is mined by sinking a 
shaft and then following the vein. Thus mined, it often contains 
much earthy matter. The purest pieces are first separated by 
hand picking, and the remainder is dumped into tanks of cold 
water; the purer ozokerite rises to the surface and is skimmed 
off, and the earthy matter, containing some ozokerite, sinks to 
the bottom. This residue is then heated in boiling water, when 
practically all of the ozokerite rises to the surface and is separated. 
The earth is finally extracted with naphtha, thereby dissolving 
the last traces of ozokerite. Ceresin, or refined ozokerite, is used 
largely as a substitute for beeswax, and is prepared by treating 
with sulphuric acid, washing with water, and neutralizing with 
caustic soda, as described under petroleum refining, and sub- 
sequent filtration through bone black or fuller's earth. It varies 
in color from white to yellow, according to the degree of refining. 
Ozokerite is sometimes distilled and worked up for paraffine wax. 

ASPHALT. The name asphalt is generally applied to that 
class of bitumens found naturally in the earth in various parts of 
the world. It consists principally of compounds of carbon and 
hydrogen, also compounds containing nitrogen, oxygen, and sul- 
phur and some mineral matter, and is considered to have resulted 
from crude petroleum. Asphalt is black in color, and melts 
easily on the application of heat. It is partly soluble in petroleum 
spirit and completely soluble in carbon disulphide, the part soluble 
in petroleum spirit being designated " petrolene," and the part 
soluble in carbon disulphide, " asphaltene." The principal uses 
are for street paving, weather-proofing, paints and japans. The 
most important production is from " Pitch Lake," on the island 
of Trinidad, which is 135 feet deep at the center and originally 



276 ELEMENTS OF INDUSTEIAL CHEMISTRY 

covered an area of approximately 127 acres, and is estimated to 
contain several million tons of asphalt. 

The asphalt residues from crude petroleum so closely resemble 
the natural asphalts that they cannot be distinguished with 
certainty. Petroleum asphalts are used principally for weather- 
proofing. 



CHAPTER XIII 
THE DESTRUCTIVE DISTILLATION OF WOOD 

For distillation purposes, usually but two classes of woods 
are used — the hard woods, such as oak, beech and maple, and 
resinous woods, such as the yellow pine and Douglas fir. The 
hard woods yield larger quantities of acetic acid and alcohol and 
the resinous woods more tar and oils. To obtain the highest 
yields of the various products sought, the proper kind of wood 
must be selected, and the supply should be large. 

TREATMENT OF THE MATERIAL PREPARATORY TO DIS- 
TILLATION. In hard wood distillation in the United States, 
the wood is cut into lengths of about 4 ft., like ordinary cord 
wood. In Europe the wood is often cut into short billets and 
then distilled. As the distillation of hard wood is now carried 
on mostly in connection with iron furnaces, large pieces of wood 
must be used in order to make a suitable charcoal. 

The practice with resinous woods is very variable. Some 
plants use cordwood, some billets, and some chips from a chipping 
machine called a " hog." 

In all destructive distillation processes, the finer the wood 
is cut the more quickly the distillation proceeds. ToMlistill very 
fine material special apparatus is needed on account of the tend- 
ency of the material to pack, thus preventing the heat from 
passing through. Usually, in a stationary retort the wood should 
not be cut in pieces less than a foot in length. As the cutting 
of the wood requires power, labor and apparatus, the advantages 
of rapid distillation are often offset by the expense of preparation. 
For the extraction of turpentine, the finer the particles of wood, 
the larger the yield, the quicker the distillation and the better 
the quality of the oil produced. If the residue is to be used for 
paper making, the chips should be of a suitable size to make the 
proper fiber. 

Manufacturing Processes. Charcoal Pit. For the pro- 
duction of charcoal only, the simplest and crudest form of dis- 
tillation is the common charcoal pit, Fig. 95. This method con- 

277 



278 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



sists of stacking up a lot of wood in a circle of 30 to 50 ft. in 
diameter and covering it with earth. These pits are made in 
various shapes and sizes. Often the wood is cut into billets and 
placed on end to form a circular stack of several layers, the 
diameter of each upper layer being less than the one imme- 
diately below it, thus forming a mound or " meiler." A passage- 
way is left to the middle of the pile so that a fire can quickly 
reach the center. The pile is covered with turf and sand, except 
near the bottom, where vents are left for the admission of air 
and also for the escape of the vapors. In this form of distilla- 
tion part of the wood is carbonized by the heat formed by the 
combustion of the other part. The water vapor is driven off 
first and the oxygen of the air present in the interstices of the 
wood is consumed. After distillation gets under way the air is 




Fig. 95. 



carefully excluded to such an extent that only sufficient is admitted 
thoroughly to char the wood without burning too much of it. 
Any part exposed by the earth falling in is quickly covered and 
only cracks enough allowed to permit the gases to escape. The 
charring is finished when the gases become light blue in color. 
The earth is then removed in small sections at a time and the 
charcoal quenched with water. 

Charcoal Kiln. In a charcoal kiln the wood is stacked either 
on end or lying down. A' firing passage is left as in the case of 
the charcoal pit. The kiln itself consists of a brick chamber, 
either beehive in shape or rectangular. It is usually made 
large enough to hold from 60 to 80 cords of wood. Some are 
lined with firebrick part way up the side. Doors are left in the 
top and bottom for charging the wood. Openings are left in the 
bottom for the admission of air, and some have a flue connec- 
tion with a stack so as to encourage the draft. Those having 



THE DESTRUCTIVE DISTILLATION OF WOOD 



279 



stacks can be forced so as to complete the distillation in two or 
three days if necessary. Usually it takes about eleven days to 
charge, distill and to cool. 

An illustration of the most common form of kiln is shown with 
stack in Fig. 96. The method of operating a kiln is similar to 
that followed with a pit. The fire is led to the middle of the pile 
and the whole allowed to heat slowly to drive out the water, 
then the holes at the bottom are closed and opened in such a 
manner as to cause the fire to spread over the entire kiln so as 
to avoid, as far as possible, the formation of brands or uncharred 
pieces. As with the pit, the presence of the light-blue vapors 
denotes the fact that most of the volatile matter has been driven 
off. The kiln is then closed up tightly with lime and allowed 
to cool. In both the pit and the kiln the vapors are lost, although 




Fig. 96. 



sometimes a condenser is used with a kiln. On account of the 
large amount of fire gases which mingle with the vapors, these 
condensers must be large and supplied with plenty of cooling 
water. The yield of valuable products is much less than when 
retorts are used. 

RETORTS. To save the volatile matter coming from the 
wood, various retorts have been devised, varying within wide 
limits, according to the kind of wood to be distilled. 

The simplest form of apparatus for saving the vapors formed 
by distillation consists of an inclosed vessel, called a retort, 
surrounded by a suitable furnace, to which heat can be applied 
by means of coal, wood, oil, gas or electricity, the vessel to be 
supplied with a vapor pipe connecting with some form of a con- 
denser. Some kind of tank is also needed in which to collect 
the condensed products. Where there is acid, the retorts are 
made of iron, the connecting pipes and condenser tubes of copper, 



280 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



^imirm/iii 



and the receiving tanks of wood or copper lined. To distill with 
steam to obtain turpentine, a furnace would not be required, 
but the other apparatus would be similar. 

The retorts used are of two distinct types, those placed 
horizontally in the furnace and those set vertically. Of the 
horizontal type there are two classes, the rectangular ovens and 

the cylindrical retorts. 
Of the vertical type 
there are three classes, 
>j^ the fixed retort, the re- 

movable retort and the 
fixed retort with re- 
movable cage. 

Of the horizontal re- 
torts the ovens are the 
most numerous — Fig. 
97. They are rectan- 
gular in shape, flat on 
the bottom and slightly 
Fig. 97. arched on top. The 

bottom is supplied with 
rails. On the sides or back are one or more openings for the 
exit of the vapors to be condensed. The wood is loaded on steel 
cars holding about two cords each and rolled into the retort. 
The ovens are about 6 ft. wide and 7 ft. high and of various 
lengths to hold two, 
three or four cars each. 
One or two coolers are 
used with each of these 
ovens, of similar shape 
to the ovens but of 
lighter material, into 
which the car of char- 
coal is withdrawn soon 
after the end of the dis- 
tillation. 





Fig. 98. 



Some of the cylindrical retorts, Fig. 98, are made 9 ft. long by 
50 ins. in diameter and will hold about a cord each. These 
retorts are charged and emptied by hand. An iron box mounted 
on wheels is used to hold the hot charcoal f and when full it is 
covered with a sheet-iron cover and the edges luted with sand or 
clay. 



THE DESTRUCTIVE DISTILLATION OF WOOD 281 




Of the vertical retorts no particular type seems to have the 
preference. The retorts are usually made cylindrical and hold 
from | to 5 cords of wood. A convenient size is about 2 cords. 
The fixed retorts remain in the 
brickwork and are attached to 
the vapor pipe of the condenser 
by one or two pipes, preferably 
one at the top and one at the 
bottom. The movable retorts are 
so arranged that they can be 
pulled out of the furnace when 
the wood is charred and allowed 
to cool unopened. Instead of 
hoisting the retort itself some 
types use a retort with remov- 
able cage, Fig. 99. Only the 
cage is removed, and as the cage 
does not have to stand the direct 
heat of the fire, it can be made 
of lighter material than the re- 
tort and the removing of the 

cage instead of the retort saves the wear and tear of the brick- 
work. In addition to this the vapor pipes are not disturbed. 

CONDENSERS. The condensers used are generally of one 
type, although other kinds might be used. The most satisfactory 
seems to be the vertical tubular condenser, which consists of 
a vapor pipe, leading to an expanding chamber at the top of 
the condenser; the necessary condensing tubes, and a bottom 
chamber for collecting the condensed matter from the tubes— 
these parts are all made of copper. The whole is contained in an 
iron or wooden shell w r hich holds the condensing water. The 
top of the condenser is supplied with a cap or removable top 
fastened by means of a yoke or bolts so that the tubes can be 
easily reached and cleaned. To the lower chamber is con- 
nected an outlet pipe which is usually supplied with a " goose 
neck " or U bend, to hold back the gases, and a top opening 
to permit the gases to escape to the furnace. The bottom of 
the condenser is made sloping, so as to drain out the tar. Some- 
times a few fractioning elements are used to remove the tar 
from the vapors, so as to make the pyroligneous acid free from 
tar, thus saving one distillation when making gray acetate of 
lime. 



282 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Worm condensers have been used, and also tubes set one 
above the other, with removable ends, but they are not as sat- 
isfactory as the tubular condenser. 

Hard-wood Distillation. Using hard wood, destructive 
distillation is practiced, the products being charcoal, acetates 
and wood alcohol. Most of the lately erected, large-sized 
plants use the oven type of retort, while some of the earlier con- 
structed plants continue to use the small cylindrical type, and 
one or two the vertical type. Some large installations are said 
to have been made, using an oven type with chambers on each 
side of the oven for receiving and discharging cars of wood and 
charcoal respectively. An attempt is being made to introduce 
special retorts for distilling sawdust. 

To operate to the best advantage it is best to heat slowly 
after the liquid starts to flow from the mouth of the condenser, 
as overheating causes a loss of volatile matter. 

The first distillate begins to come over at about 320° F. 
and consists of furfural, water, and very little acid. The watery 
distillate is known as " pyroligneous acid." The percentage 
of acid increases with the temperature until the tar begins to 
distill, then it begins to drop off slightly. Meanwhile uncon- 
densable gases are formed which are piped to the furnace and 
burned. During the early stages of the distillation the color 
of the flame of the burning gases is blue, due to the carbon 
monoxide present, while later the color becomes yellow, due to 
the presence of the heavier hydrocarbons. The end of the 
operation is indicated by the falling off of the quantity of the 
distillate at the mouth of the condenser, by the temperature 
inside the retorts (about 800° F.), and by the color of the shell 
of the retort. The character of the distillate also indicates 
the end of the distillation, the tarry products being strongly 
in evidence. When cars or cages are used, the charcoal is with- 
drawn hot, thus saving the heat of the brickwork for the next 
charge. The conditions should be regulated so that each retort 
can be charged once every twenty-four hours. 

The Distillation of Resinous Wood. The distillation 
of resinous wood requires retorts varying in size and shape with 
the methods of operation and the products sought. The chief 
commercial products obtained by the distillation of resinous 
woods are turpentine, tar and charcoal. Soft woods yield an 
acid solution much weaker in acetic acid and alcohol than hard 
woods., thus the proportion of water distilled is greater. On 



THE DESTRUCTIVE DISTILLATION OF WOOD 283 

this account the pyroligneous acid from resinous woods is not 
usually saved. 

There are several methods of treating resinous woods to 
obtain the various products. Of them the employment of steam 
distillation is the most general, although extraction by means 
of volatile solvents is sometimes used. 

The destructive distillation of hard wood is carried on in 
a very similar manner to the treatment of soft woods. 

The greatest variation seems to be in the method of extract- 
ing the turpentine. As this substance is apt to become con- 
taminated with tarry products, giving it a bad odor and color, 
considerable care is necessary to produce it. To avoid this 
contamination, some use two condensers, one for the turpentine, 
and the other for the tar and pyroligneous acid. Others collect 
the turpentine in one tank and the other products in another. 
Usually the change from turpentine to the other products is 
made when the temperature reaches 320° F., or when the wood 
begins to decompose. 

The operation is carried on at first at a low temperature 
so as not to char the wood. The turpentine and rosin exist 
already formed and are not products of the decomposition of 
the wood. By the influence of heat the turpentine distills, 
carrying with it part of the rosin. Sometimes steam is added 
to help carry over the vapors. As the heat increases part of 
the rosin decomposes and rosin oil distills over. When the wood 
begins to char, the pyroligneous acid begins to form and the 
distillation is carried on from this stage exactly as in the case 
with hard-wood distillation and the products all collected in 
one tank. 

THE STEAM PROCESS. To extract the turpentine which is 
already present in the wood it is only necessary to employ such 
agents as will volatilize it. A mixture of turpentine and water 
boils at 95° C, so if steam be passed through chipped wood 
in a suitable retort and the temperature maintained above 
95° C, a mixture of oil and water vapor will distill and can be 
condensed in the ordinary manner. This is an old method of 
distilling finely divided wood that has been given much atten- 
tion recently. Much ingenuity has been used to devise suitable 
mechanical arrangements for carrying on the process successfully. 
The requirements are a wood- chipping and elevating system 
that will deliver the wood to the retorts; an easy method of 
discharge from the retorts for the steamed wood; and the 



284 ELEMENTS OF INDUSTRIAL CHEMISTRY 

proper conveying machinery to remove the discharged chips 
to a bin or to the boilers. Considerable steam is needed for 
this process. 

Usually, a vertically placed or slanting retort is used with 
an opening on top for the entrance of the wood, and with a large 
discharging device at the bottom. Various forms of rotating 
retorts are also used. The retorts are connected to suitable 
condensers varying from one another in some details, but all 
based on the solvent power of some alkali or volatile oil. The 
alkali process consists in dissolving the rosin in soda solution and 
neutralizing the solution with acid to regain the rosin. This was 
tried on a semi-commercial scale but was abandoned in favor of 
the volatile solvent process. The alkali process was found to be 
cheaper, so the plant is expected to change back to the alkali 
process. 

The extraction with volatile solvents has been carried out on 
a large scale by one company and on a smaller scale by other 
companies. This process consists in grinding the wood, steaming 
out the turpentine, and extracting the remaining pine oil and 
rosin with a neutral volatile hydrocarbon such as gasolene. The 
gasolene solution is distilled in indirect steam heat to remove 
the light oils, followed by live steam to remove the heavy mineral 
oils and pine oils, a comparatively high temperature being main- 
tained by steam in a closed coil. All the gasolene is not recovered, 
the loss being one of the chief items of expense attending the 
operation. 

To Obtain Refined Products. The condensed liquor 
from the destructive distillation processes consists of three layers, 
the upper layer of tarry oils, the intermediate layer of pyro- 
ligneous acid, and the bottom layer of tar. Sometimes with 
resinous woods the line of demarcation is not very well defined. 
In such cases the separation is difficult, without distilling. A 
centrifugal separator could be used to advantage. 

The crude product coming from the wood in the steam process 
consists of crude turpentine as an upper layer and of water as a 
lower layer. In all the processes the separation is effected as 
far as possible by gravity, the different products being drawn 
off at the respective levels. 

CRUDE ACETATES. The pyroligneous acid contains fatty 
acids, chiefly acetic, varying from 4 to 10 per cent, about 1 to 12 
gallons of wood alcohol to the cord of wood used, some acetone, 
light oil, metacetone and other ketones, aldehydes and tarry 



THE DESTRUCTIVE DISTILLATION OF WOOD 285 

products. To obtain the various products, different means are 
pursued according to the quality of products to be made. These 
are brown acetate of lime or lead, gray acetate of lime, acetate 
of soda, acetic acid and refined wood alcohol. 

To make brown acetate of lime, the acid is simply neutralized 
with lime and the insoluble tarry products produced skimmed off. 
The solution of acetate is distilled in an iron or copper still until 
the wood alcohol is collected, when the remaining liquor is 
evaporated to dryness and partially charred to destroy tarry 
matters. 

To make gray acetate of lime, the liquor is sent to an acid 
still, a copper still with or without special fractionating column. 
The alcohol distills first and may be collected separately until the 
temperature in the sill approaches 100° C. or the sp.gr. of the 
distillate is 1. The acid is then distilled and may be passed 
directly as a vapor through milk of lime, or condensed and caught 
separately, when it is known as distilled wood vinegar. This is 
neutralized with lime. As some of the acid will distill with the 
wood alcohol, both are usually condensed together and neutral- 
ized with lime. The liquor is then distilled in a fractionating 
still to recover the alcohol. The acetate liquor is evaporated to 
a paste in suitable iron pans, and then spread on top of the ovens 
to be thoroughly dried and partially charred. Crude hydro- 
chloric acid is often added before evaporation and the liquor 
drained from the deposit so formed. The evaporating pans, 
made of copper, are usually provided with a set of stirrers to 
prevent the acetate from sticking to the bottom. The tarry 
matter rising to the surface is removed through a sliding door. 
When the specific gravity (measured hot) reaches 1.116 the 
separation of acetate begins and gradually the mass forms a thick 
paste, which is removed and spread on fiat iron pans to be dried. 
Some finish the drying in rooms heated by the waste furnace or 
retort gases. The residue in the stills is " boiled tar," and is 
removed at intervals as it accumulates. 

Acetate of soda is made in a similar manner to acetate of lime. 
Sodium carbonate is added, in small portions at a time to avoid 
too much effervescing, to distilled wood vinegar until the acid 
is neutralized. The tarry substances appearing on the surface 
are removed and the brown fluid, after clarifying by standing, is 
drawn off into shallow iron pans, which are heated by the fire gases 
from the retorts or by steam. The liquid is evaporated to 1.23 
sp.gr., then crystallized in sheet-iron boxes. The crystals are 



286 ELEMENTS OF INDUSTRIAL CHEMISTRY 

drained from the mother liquor and then centrifuged. By cal- 
cining these crystals, redissolving and recrystallizing, a very pure 
salt is obtained. Sometimes the solution is filtered through bone 
black or boiled with 10 per cent of bone black and after recrystal- 
lizing and centrifuging an entirely pure salt is obtained. 

WOOD ALCOHOL. The crude wood alcohol is treated with 
lime and settled, the clear liquor being redistilled in column 
stills until of about 82 per cent by volume passes over. By 
again distilling, a product of 92 to 95 per cent can be easily ob- 
tained. However, to make alcohol that is miscible with water, it 
is advisable to dilute the alcohol until the specific gravity reaches 
0.934 and allow the mixture to rest for a few days, when the 
greater portion of the hydrocarbons separate as an oily layer on 
the top and can be drawn off. The alcoholic fluid left is distilled 
over lime and makes strong alcohol that does not become turbid 
upon the addition of water. The oily fractions are mixed together 
and redistilled separately, when a further quantity of alcohol is 
obtained. Only the portion miscible with water is saved, the 
other portions being worked over. The first runnings of the 
distillate are more or less colored, but the middle fractions are 
colorless and yield good alcohol. After the middle portion distills 
the alcohol begins to contain oil and it becomes non-miscible. 
Subsequently, the distillate becomes turbid and finally a mixture 
of oil and water comes over, which separates into two layers. 
None of these processes serves to remove all the acetone. To do 
this several methods are used. One is to form a compound of 
wood alcohol and calcium chloride, which is stable at 100° C. 
By gently heating, the acetone is driven off, and then by adding 
water and raising the temperature to 100° C. the calcium chloride 
compound decomposes and the methyl alcohol distil.s. Another 
method is to add caustic potash and iodine until the yellow color 
disappears, then to distill. The watery alcohol is repeatedly 
rectified over lime, and finally over metallic sodium or phosphoric 
anhydride to remove the last traces of water. 

THE CRUDE TAR. The tar from hard woods is usually burned 
for fuel, but that which is to be utilized is washed with water or 
dilute milk of lime, in order to wash out the acid. It is then ready 
for further treatment. The tar from resinous woods is distilled 
with live steam in a copper tar still until the oils are removed. 
If these oils contain turpentine, as they would when the distillate 
is collected together, they are specially refined. When thick 
enough the tar is ready for barreling. 



THE DESTRUCTIVE DISTILLATION OF WOOD 287 

TAR OILS. There is a small but increasing demand for tar 
oils as insecticide and disinfectants. To obtain tar oil from the 
tar, it is distilled in a wrought- or cast-iron vessel sometimes 
provided with a stirrer. The general shape of the still may be 
similar to a turpentine still, or the still may be a horizontal 
cylinder set in brickwork. The still is heated slowly and the 
distillate collected until the specific gravity of the tar oil reaches 
about 0.98, when the receiver is changed. Some of the oils present 
in the tar distill unchanged, while the heavier products are broken 
up to a greater or lesser degree, forming coke and gas. Follow- 
ing the light oils, a heavy oil comes over, having a specific gravity 
of upward of 1.01 and of a yellowish-green color. The distilla- 
tion is sometimes carried on until nothing but coke is left in the 
still, but it is usually better to stop with the production of pitch, 
which can be drawn out hot from the still. This is run out on 
iron plates to cool, care being taken to prevent ignition. The 
condensate is sometimes divided according to the temperature 
of distillation, the light oils being collected up to 240° C. and the 
heavy oils between 240 and 290° C. The heavy oil contains 
most of the creosote, which is extracted from the heavy oil by 
means of caustic lye of about 1.2 sp.gr. The hydrocarbons are 
boiled out and the creosote separated by neutralizing with sul- 
phuric acid. The treatment is repeated and the final creosote 
distilled, the product coming over between 200 and 220° C. being 
called commercial wood creosote. To further purify it, it is oxi- 
dized with a mixture of dichromate of potassium and sulphuric 
acid and again distilled. 

The crude oil in the distillate from the steam treatment of 
pine tar is often saved. It varies in color from light yellow to 
brown, exposure to the air causing the color to become much 
darker. A number of substances are present, including the oils 
coming from the distillation of the turpentine and from the 
destructive distillation of the rosin in the wood. The crude oil 
also contains considerable quantities of creosote and tar prod- 
ucts. To remove these, the oil is redistilled in a still of similar 
shape and construction to the tar still — only smaller. The 
oil comes over with only a slight coloration. To prevent this 
color, the crude oil is sometimes treated with chemicals such as 
caustic soda, lime, permanganate, sulphuric acid and the like 
before being distilled. These substances usually fail to remove 
either odor or color to any great extent. When the percentage 
of turpentine in the wood oil is large, the crude oil is washed 



288 ELEMENTS OF INDUSTRIAL CHEMISTRY 

with oil or alkali in an agitator and often distilled in a column 
still similar to the still used in refining wood alcohol. 

TURPENTINE. The crude wood turpentine caught separately 
when wood is distilled by any method, is usually refined in order 
to make a marketable article. When the oil is very impure a 
still with a short column is desirable. When the oil is relatively 
pure and almost colorless like that obtained in the steam dis- 
tillation, a simple distillation is all that is needed. The oil 
should be tested as it comes from the still and when the specific 
gravity reaches 0.875 the receiver should be changed or the 
distillation ended. The distillate is often divided into three 
portions, the first fraction consisting of the light oils, corre- 
sponding to turpentine, the second fraction being a mixture of 
turpentine and light pine oils and the third fraction being very 
heavy pine oils. The middle fraction is redistilled and yields 
an additional amount of turpentine. A heavy oil called pine 
oil remains behind, which can be distilled at a higher tempera- 
ture. This oil should not be mixed with the turpentine, as the 
mixture does not dry readily. 

PINE OILS. The heavy oils accompanying wood turpentine 
are called pine oils. They are divided into two grades, water 
white and yellow. The darker grades are heavier and are of the 
most value. They are used in medicine and as solvents. Ter- 
pineol is one of the chief ingredients. 

ACETIC ACID. This acid is not usually prepared directly 
from wood vinegar, although it can be with considerable trouble. 
It is usually prepared by the decomposition of some acetates. 
Some of the acetates are decomposable by heat into acetic acid 
and oxides, for example lead acetate. The diacetates of sodium 
and potassium yield a very concentrated solution of acid when 
heated. 

Usually, it is best to start with acetate of lime or soda and to 
distill with concentrated hydrochloric acid in a copper still, care 
being taken to have an excess of the salt in the still. When 
brown acetate of lime is used, it is previously roasted at a low 
temperature. The acid formed is colored and contains about 
50 per cent of anhydrous acid. With dilute hydrochloric acid 
in the still, the acetic acid is purer, but contains only 30 per cent 
anhydrous acid. Often the acid is distilled in Marx vessels 
and filtered in towers through freshly burned charcoal. To 
obtain stronger acid, the weak liquor is redistilled and the stronger 
parts of the distillate caught separately. Any HC1 that may be 



THE DESTRUCTIVE DISTILLATION OF WOOD 289 

found in the distillate can be removed by rectifying over acetate 
of lime or soda. Sulphuric acid could be used to effect the dis- 
tillation, but the operation is not so smooth and the distillate is 
apt to contain sulphur dioxide. 

Glacial acetic acid can be prepared by distilling 12 parts by 
weight of pure anhydrous sodium acetate with 11 parts of con- 
centrated sulphuric acid. The first portion of the distillate is 
rectified over sulphuric acid and pyrolusite to remove traces of 
sulphurous acid. The last portion, which is frequently empy- 
reumatic, is collected by itself. The water in the 50 per cent acid 
can be removed by distilling with anhydrous calcium chloride 
and cooling the distillate, whereby one portion crystallizes. 
The liquid portion is drawn off and again distilled over calcium 
chloride. By distilling strong acid over fused and coarsely 
powdered potassium acetate and changing the receiver at 120° C 
the glacial acetic acid will pass over in the last portion. This 
is again rectified over potassium acetate and the distillate cooled 
to about 16° C. to crystallize the acid. Stoneware vessels are 
needed to carry on the distillation, as the acid strongly attacks 
metals. 

ACETONE. On a commercial scale, acetone is made by the 
dry distillation of gray acetate of lime at !290 to 400° C. in retorts 
which are connected with a cooling apparatus. When brown ace- 
tate is used it is previously roasted at 230° C. The first runnings 
are weak in acetone , but the percentage increases with the tem- 
perature. The distillate separates into two layers, the " heavy 
acetone oils " on top and the lighter oils dissolved in water on the 
bottom. The yield is about 20 per cent of the calcium acetate. 
The crude acetone is treated with lime and distilled in column 
stills in a similar manner to wood alcohol, a nearly pure product ■ 
being obtained. 

The nearly pure acetone can be purified by treatment with 
sodium bisulphite and then crystallizing the compound formed. 



CHAPTER XIV 

OILS, FATS AND WAXES 

CLASSIFICATION OF FATS. The term oil is used for sub- 
stances differing widely both in composition and properties, and 
in this chapter the fatty oils only will be considered. Fats and 
fatty oils consist essentially of compounds of the higher fatty 
acids in combination with glycerol, and are termed glycerides. 
Their composition was first placed on a scientific basis by 
Chevreul, who in the early part of the last century showed that 
when a fat such as tallow or lard was converted into soap by the 
action of sodium or potassium hydroxide, the fat was decomposed 
into glycerine and fatty acids, the latter combining with the alkali 
to form the soap, while the glycerine, remaining free, was separated 
in the lyes. The three most commonly occurring glycerides are 
stearin, palmitin (of which tallow chiefly consists) and olein 
(the principal constituent of olive oil). The conclusions of Che- 
vreul as to the composition of fats where subsequently confirmed 
by Berthelot, who succeeded in producing the glycerides syn- 
thetically by heating the fatty acids with glycerine under pressure 
in sealed tubes. Heating together, for example, stearic acid 
and glycerine, he obtained stearin, according to the equation: 

3Ci8H3502H + C3H5(OH)3 = C 3 H5(Ci8H8502)3 + 3H20. 

From their physical appearance it is not possible to give a 
definite classification, for what would be considered a solid fat 
in a temperate climate might be a liquid in a warmer locality. 
Roughly, however, we may class certain ones as liquid fats or 
oils, and others as solid fats, or fats. 

" The most convenient classification of fats (fatty oils and 
solid fats) for practical purposes, appears to be given by arranging 
them according to the magnitude of the iodine value. This 
principle leads, without unduly forcing it, to a natural subdivision 
into liquid fats and solid fats, the former being differentiated from 
the latter by the considerably higher iodine value, Hence, an 

290 



OILS, FATS AND WAXES 291 

arrangement based on the magnitude of the iodine value would 
include the older system of classification according to consist- 
ency. Inasmuch as the magnitude of the iodine value stands in 
close relationship to the absorption of oxygen, or, in other words, 
to the drying power, classification on the iodine value would also 
include the older subdivision into drying and non-drying oils." 
(Lewkowitsch.) 

Arranged in this manner are the following subdivisions : 

I. Liquid Fats and Fatty Oils. 

A. Vegetable oils B. Animal oils 

1. Drying oils 1. Marine animal oils 

2. Semi-drying oils (a) Fish oils 

3. Non-drying oils (b) Liver oils 

(c) Blubber oils 
2. Terrestrial animal oils 
II. Solid Fats 

A. Vegetable fats B. Animal fats 

1. Drying fats 

2. Non-drying fats 

Classification of Waxes. Our comprehension of the 

generic term " wax " is based in considerable measure on the 
physical characeristics of the oldest known wax; namely, com- 
mon beeswax. It has been suggested that the term wax is 
defined as applied to more or less unctuous, fusible, variably 
viscous to solid substances, having a characteristic " waxy " 
luster, which are insoluble in water but usually soluble in car- 
bon disulphide, benzol, etc., and which are extremely suscep- 
tible to changes in temperature and whose origin, composition, 
and color are variable. 

Thus under this definition are included the class of waxy 
bodies which consist of mono or dihydric alcohols united with 
the higher fatty acids to form esters (beeswax, carnauba wax, 
etc.), as well as glycerides of a "waxy" appearance, such, for 
example, as Japan wax; and the hydrocarbon waxes paraffine, 
ceresin, ozocerite and the like. 

Waxes may be grouped as follows; 

A. Liquid waxes B. Solid waxes 

1. Vegetable waxes 

2. Animal waxes 



292 ELEMENTS OF INDUSTRIAL CHEMISTRY 

CONSTITUTION OF THE FATS. The fats as stated are com- 
binations of glycerol with fatty acids. Glycerol being a tri- 
hydric alcohol, will combine with one, two, or three acid radicles, 
thus forming mono-glycerides, di-glycerides, and tri-glycerides. 
The last class, however, is the most important, as it is this con- 
dition which is supposed to exist in the neutral fats. The fol- 
lowing graphic formulas will more clearly emphasize the three 
possible combinations: 

H 

I 

Monostearin. C 1 7H3 5 COO— C— H 

I 
HO— C— H 
HO— C— H 

I 
H 

H 

I 
Distearin C17H35COO— C— H 

I 
C17H35COO— C— H 

I 
HO— C— H 

I 
H 

H 

I 
Tristearin. C17H35COO— C— H 

I 
C17H35COO— C— H 

I 
C17H35COO— C— H 

I 
H 

It will be seen that not only is it possible to have compounds 
in which one acid enters into the combination, but also others, 
known as mixed glycerides, in which two or even three different 
acid radicles may be joined to one glycerol group. This is 
thought by some to account for the fact that practically all of 
the common oils are mixtures, rather than smple esters. Our 



OILS, FATS AND WAXES 293 

present knowledge, however, does not warrant any definite 
conclusion in this matter. 

The fatty acids are all lighter in weight than water. Those 
having less than ten carbon atoms may be distilled, and are 
known as the volatile fatty acids. Those containing more 
than ten carbons cannot be distilled without decomposition and 
are known as non-volatile fatty acids. The oils containing 
the saturated acids do not undergo any marked change when 
exposed to the air. On the other hand, those which contain 
the unsaturated acids become gummy, and in certain instances 
when exposed in thin layers form dry, hard films. This change 
is called drying, and is most marked in the case of those oils 
containing giycerides of linoleic, linolenic, clupanodonic and 
ricinoleic acids. 

VEGETABLE OILS. The usual method of obtaining the oils 
is by crushing that part of the plant richest in oil, and subse- 
quently pre sing the ground pulp thus obtained. Extraction with 
benzine or other solvent is also employed. The crushing may 
be secured by means of the edge-runner, or by means of heavy 
steel rollers arranged in vertical series. The crushed material 
is then placed in canvas bags, and subjected to hydraulic pressure 
The first pressing is usually done in the cold, as a lighter color 
and better quality is thus obtained. During the second pressing 
the pulp is heated, thereby producing a larger yield, but of an 
inferior quality. By further heating a final oil is obtained 
known commercially as " foots." The extraction process con- 
sists in treating the ground pulp, contained in closed vessels, 
with benzine, naphtha or other solvents. The extract is sub- 
jected to distillation in order to recover the solvents, leaving 
the fats in the still. Although this method gives a larger yield 
than is possible by pressing, it is not generally employed on 
account of the risk from fire, the cost of installation, and im- 
possibility of directly using the press cake as a cattle food. 

VEGETABLE DRYING OILS. Drying oils are characterized 
by their power to absorb oxygen from the air, thus forming an 
elastic film. The amount of this absorption in the main is in 
proportion to the iodine value; so that we may roughly judge 
of the drying quality of an oil from its iodine number. 

Perilla Oil. This oil occurs to the extent of 35.8 per cent 
in the nuts of the Perilla ocymordes, a plant indigenous to East 
India, Manchuria, and Japan. It has the highest iodine value 
of any known oil, and in odor and taste resembles linseed oil. 



294 ELEMENTS OF INDUSTRIAL CHEMISTRY 

TABLE OF CONSTANTS FOR DRYING OILS 



Name of Oil. 



Perilla 

Linseed 

Tung 

Hemp 

Poppy 

Sunflower. . . 
Tobacco seed. 



Oil 
Con- 
tent of 
Seed, 

Per 
Cent. 



35.8 

38-40 

40-41 

30-35 

41-50 

21-22 

38-40 



Specific Gravity. 



0.9306 

9315-45 

0.9360-432 

0.9255-80 

0.9240-70 

0.9240-58 

0.9232 



20° C. 
15° C. 
15° C. 
15° C. 
15° C. 
15° C. 
15° C. 



Saponifi- 
cation 
Value. 



189.6 

192-195 

193 

192.5 

195 

193.5 

170 



Iodine 
Value. 



206.1 

171-201 

150-165 

148 

133-143 

119-135 

118.6 



Refractive Index. 



1.4835 
1 . 5030 
1.4780 
1 . 4586 
1.4611 



22° C. 
19° C. 
15.5° C. 
60° C. 
60° C. 



Its drying quality, however, is, it is claimed, inferior to linseed 
oil, due to its peculiar property of forming drops when spread 
oh a hard surface. Recent experiments, on the other hand, do 
not bear out this statement. 

Linseed Oil. This ia obtained from the seeds of the flax 
plant, grown extensively in Russia, India, Argentina, Canada, 
and the United States. On cold pressing, a light yellow oil 
is obtained, used to a limited extent as an edible oil. By far 
the greatest quantity, however, is used in the manufacture of 
paint and varnish. The chemical composition of Unseed oil is 
not well known, although indications point to about 10 per 
cent of glycerides of solid fatty acids, equal parts palmitic and 
myristic acids. The liquid glycerides consist of 5 per cent of 
oleic acid, 15 per cent of linoleic acid, 15 per cent of linolenic 
acid, and 65 per cent of isolinolenic acid. Linseed oil is now 
converted by hydrogenation into a solid fat, which serves as 
a substitute for tallow in soap making. 

Tung Oil. This oil is often spoken of as " Chinese wood 
oil." It is obtained from the seeds of Aleurites cordata, a tree 
indigenous to China and Japan. The oil varies to some extent 
according to its source. The seeds are usually roasted, broken 
into a powder and pressed. The cold pressed oil is pale yellow, 
and is known in the trade as " white tung oil." That resulting 
from hot pressing is dark in color, and termed " black tung 
oil." The raw oil has a peculiar odor suggestive of ham. Its 
chemical constitution differs from linseed in that it consists almost 
wholly of glycerides of oleic and elaeomargaric acids. 

Tung oil is used principally in the manufacture of varnishes 
and linoleum. When incorporated with ordinary rosin and 
suitably thinned, a varnish is obtained which is not affected 



OILS, FATS AND WAXES 295 

readily by water, while varnish made with rosin and linseed oil 
alone is quickly turned white by contact with water. In con- 
sequence of this behavior of tung oil, it has become very popular 
with the varnish maker as a means of producing cheap but good 
varnish. When heated to 230° C. and over, the oil coagulates 
to a transparent solid which is elastic under compression, and 
this product has been recommended as a rubber substitute called 
factis. 

Hemp Seed Oil. The source of this oil is the hemp plant, 
Cannabis sativa. The color of the fresh oil is light green, becom- 
ing brownish-yellow on standing. The solid glycerides of hemp 
oil are claimed to be those of stearic and palmitic acids. The 
liquid glycerides contain linoleic, oleic, linolenic, and isolin- 
olenic acids. It is used as a paint oil, for making soft soaps, and 
low grades are employed for certain varnishes. 

Poppy Oil. To obtain this oil the seeds are pressed cold, 
thus producing a product almost colorless, or very pale golden 
yellow, known in the trade as " white poppy seed oil." That 
expressed at a higher temperature is known as " red poppy seed 
oil." It is cultivated largely in Asia Minor, Persia, India, Egypt, 
and Russia. It is used largely as a salad oil, and in the manufac- 
ture of artists' colors. 

Sunflower Oil. This oil is obtained from the seeds of the 
Helianthus annuus. It is of a mild taste, pleasant odor, and 
a pale yellow color. It is raised extensively in Russia, Hungary, 
India and China. It is employed in soap making, and for the 
manufacture of varnish. This oil does not dry as readily as those 
previously mentioned. 

Tobacco Seed Oil. The oil obtained from the seed of the 
tobacco plant is of a pale greenish-yellow color, and dries very 
readily. On account of its high price it has never found any 
commercial application. 

Vegetable Semi-drying Oils. These oils form a connect- 
ing link between the drying oils and the non-drying oils, although 
it is difficult to say to which class they belong. Chemically 
they differ from the drying oils by the presence at the most only 
of small amounts of linolenic acids; and from the non-drying oils 
by the linoleic acid they contain. 

Soja Bean Oil. This oil is also known as soy bean oil. It is 
obtained from the seeds of several varieties of the Soja hispida, 
a plant growing in China, Manchuria and Japan. The whole 
fruit consists of a hairy pod, containing small round, yellow seeds, 



296 ELEMENTS OF INDUSTRIAL CHEMISTRY 

TABLE OF CONSTANTS FOR SEMI-DRYING OILS 



Name of Oil. 



Soja bean 

Pumpkin seed. 

Corn 

Cotton seed. . . 

Sesame 

Croton 

Rape" 

Castor 



Oil 
Con- 
tent of 
Seed, 
Per 
Cent. 



18 
35-37 
6-10 
24-26 
50-57 
53-56 
33-43 
46-53 



Specific Gravity. 



0.9242-70 
0.9237 
0.9213-55 
0.9220 
. 9230-37 
. 9500 
0.9132-68 
0.9600-79 



15° C. 

15° C. 
15.5° C. 

15° C. 

15° C. 

15° C. 
15.5° C. 
15.5° C. 



Saponifi- 
cation 
Value. 



192.7 
188.4 
188-193 
193-195 
189-193 
210-225 
170-179 
183-186 



Iodine 
Value. 



121.7 
123-130 
113-125 
106-110 
103-108 
102-104 
94-102 
83-86 



Refractive Index. 



1.4762 

1.4723-38 

1.4750-70 

1 . 4743-52 

1.4748-62 

1.4768 

1.4720-57 

1.4799 



15.5° C. 
25° C. 
15.5° C. 
15° C. 
15° C. 
27° C. 
15° C. 
15° C. 



slightly smaller than the ordinary pea. Green and black varieties 
also exist. The seed or bean contains 16-19 oer cent of oil and 
the commercial yield is about 13 oer cent. The raw oil is deep 
brown in color and is not much improved by alkali treatment 
except when bleached. The odor and flavor are slight and not 
unpleasant, but the keeping qualities of the oil are not particularly 
good, and on storage a nauseous taste is likely to develop after a 
time. The oil is employed for edible purposes, although in a 
limited way. It is used in soap making, and has been tried as a 
paint oil, but its " greasy " properties have not led to extensive 
use in this field. Soja oil hydrogenates readily, forming a hard 
fat. 

Pumpkin Seed Oil. In South Russia the seeds of the Cucur- 
bito pepo are roasted, and the oil expressed in the hot condition. 
This produces a viscous product of a deep red color. The cold 
pressed oil has a greenish color and a slight red fluorescence. The 
cold pressed oil is used for edible purposes, while the inferior 
grades serve as burning oils. 

Corn Oil. This oil is obtained from the germ of the maize 
plane Zea mays, during the manufacture of corn starch. The 
freshly prepared oil has a pale yellow color, and may be readily 
identified by its taste, which is similar to that of corn meal. 

The keeping qualities of the oil are very good when refined, 
but the crude oil is rapidly hydrolized if meal be present. By 
careful refining and deodorizing with superheated steam, an 
edible product is obtained which has a very pleasant taste and 
whose keeping qualities are good. This grade of oil is used in 
cake and biscuit making and for oiling bakers' pans, also in mar- 
garine and as a salad oil. Hydrogenated corn oil serves as a 



OILS, FATS AND WAXES 297 

satisfactory stiffening ingredient in lard compound. Corn oil 
is used quite extensively in soap making and to a more limited 
degree in the manufacture of paint. The output of corn oil is, 
however, almost insignificant in comparison to that of cotton 
seed oil. 

Cotton Seed Oil. This oil is obtained from the seed of the 
cotton plant, extensively cultivated in the United States, Egypt, 
East India, and other countries. The oil as it comes from the 
hydraulic press varies in color from yellowish brown to a dark 
ruby or blackish red, depending on the nature and condition 
of the seed from which the oil has been expressed. It contains 
mucilage, fine meal or " mealy matter," coloring and tarry 
material. Some of these impurities are due to the effect of mois- 
ture and heat in pressing the oil from the cooked seed. Crude 
oils containing under one per cent of free fatty acid and derived 
from selected seed are used in the manufacture of butter oils. 
Great care has to be taken in the preparation of butter oils to 
preclude the development of any unpleasant taste or odor. 
When about 1 or 2 per cent of fatty acid is present hi the crude 
oil refining is earned out to produce what is known as prime 
yellow oil. Above 2 per cent of fatty acids, there is more diffi- 
culty in removing the color, and the oil is not as suitable for 
edible purposes. Crude oil may contain as high as 7 or 8 per 
cent of free fatty acids in case the seed has become damaged by 
heating, etc. The losses occurring in the refining of the crude 
oil varies with the proportion of free fatty acids and usually 
runs from 7 to 10 per cent. Improved methods in refining are 
tending to reduce this loss. 

Cotton seed oil is used in large quantities for edible purposes, 
but ow 7 ing to popular prejudice it seldom appears under its true 
name. We may find it on the open market as " table oil," 
" salad oil," " sweet nut oil," as well as under a score of other 
designations. Large quantities of the cotton seed stearine are 
employed in the manufacture of " oleomargarine," butter com- 
pounds, butter substitutes, lard compounds, and lard substitutes. 
Cotton seed oil, being cheap, is often used as an adulterant for 
the more expensive oils, such as olive, peanut and other edible 
oils. One of its most imooitant uses is in the manufacture of 
toilet and laundry soaps. 

Sesame Oil. This oil is obtained from Sesamum orientate, 
extensively grown in India, China, Japan, the Levant and West 
Africa. The cold pressed oil is of a light yellow color, with a 



298 ELEMENTS OF INDUSTRIAL CHEMISTRY 

pleasant taste, so that it is used to some extent for edible purposes. 
In some countries the legal requirement is made that sesame oil 
form a constituent of margarine in order to facilitate the detection 
of margarine in butter. The hot pressed oil is used largely in 
soap making. 

Croton Oil. Croton oil is obtained from the seeds of Croton 
tiglum, a tree grown on the Malabou Coast, in Southern Asia, 
and in China. The oil varies in color from yellow, orange or 
brown according to age. It has a nauseating odor, a burning 
taste, and a very powerful purgative action. Its chief use is in 
pharmaceutical preparations. 

Rape Oil. There are several varieties of this oil, depending 
upon the place of cultivation. The oil is obtained from the 
seeds of Brassica campestris. 

In the trade this oil is called colza oil. The crude oil is 
dark brown and may contain a considerable proportion of free 
fatty acids. The refined oil is pale yellow and is very viscous, 
depositing more or less stearine on standing. The taste is 
unpleasant and the odor characteristic. Refined cold drawn oil 
is sometimes used for edible purposes, while the inferior qualities 
find an outlet as lubricants and illuminants. Rape oil as well as 
cotton and corn oil are converted into rubber substitutes or 
factis by treatment with sulphur chloride or by heating with 
sulphur. Rape oil is also " blown " with air to produce thick- 
ened products. 

Castor Oil. This oil is obtained from the seeds of Ricinus 
communis, a plant grown extensively in East India, Java, the 
Mediterranean countries, and the United States. The cold 
pressed oil is used for medicinal purposes. The lower grades 
are used very extensively in manufacturing operations, such as 
leather dressings, and in the sulphonated condition is known 
as " soluble oil " " Turkey red oil " or " monopol oil." Castor 
oil is a colorless or pale greenish oil with a mild taste. 

It has a high viscosity and finds some application in lubri- 
cants, although by no means devoid of gumming properties. Sul- 
phur unites readily when heated with it, forming rubber-like 
compounds. The hydrogenated product is very hard and has 
found a use in the manufacture of insulating materials. A peculiar 
property of castor oil is its miscibility with alcohol. Unlike 
most other oils it does not dissolve readily in petroleum ether. 
By heating to a rather high temperature the oil becomes poly- 
merized and is then miscible with petroleum ether and mineral oils, 



OILS, FATS AND WAXES 



299 



Vegetable Non-drying Oils. The oils in this class have 

a lower iodine number than those of the two preceding classes. 
They do not become gummy when exposed to the air at ordinary 
temperature, although they all thicken on heating. 



Name of Oil. 


Oil 
Con- 
tent of 
Seed, 
Per 
Cent. 


Specific Gravity. 


Saponifi- 
cation 
Value. 


Iodine 
Value. 


Refractive Index. 


Peach kernel . . 

Almond 

Peanut 

Olive 

Olive kernel. . . 


32-35 
45-55 
43-45 
40-60 
12-15 


0.918 

0.9215 

0.9175 

0.9195 

0.9170- 

0.9209 

0.916-18 

0.9184- 
0.9191 


15° C 

15° C 
15° C 
15° C 
15° C 


191.5 
199.3 
191.3 
185-196 
183 


93.3- 
100.3 
100.7 

94.7 

79-88 
87.4 


1.4713 

1.4731 

1.4766 

1.4698- 
1.4716 

1 . 4682 


15° C 

15.5° C 
15.5° C 
15° C 
25° C 



Peach Kernel Oil. This oil is obtained from the kernel of the 
peach, is of a pale yellow color, and greatly resembles almond oil. 
Its chief use is as an adulterant for almond oil. 

Almond Oil. Almond oil is expressed from bitter almonds, 
which yield more oil than sweet almonds, although both oils are 
practically identical. The source of this oil is Morocco, Canary 
Islands, Portugal, Spain, France, Italy, Sicily, Syria, and Persia. 
Its chief use is in pharmaceutical preparations. 

Peanut Oil. This product is also known as earthnut oil and 
arachis oil. It is obtained from the seeds of Arachis hypogcea, 
commonly known as peanut. It is largely cultivated on the west 
coast of Africa, India, and the United States. The nuts are 
shelled and the inner red skin separated as completely as possible 
from the true kernel. The kernels are then pressed. The oil has 
a golden yellow color and the edible varieties are usually bleached 
to a very pale color. The cold-pressed oil is nearly colorless, has 
a pleasant flavor and is largely used as a salad oil. The inferior 
qualities are used in soap making. 

Olive Oil. The oil is prepared from the fruit of the olive tree, 
both by expression and extraction. The commercial product 
varies from colorless to golden yellow and dark green, according 
to the variety of tree, degree of ripeness, manner of gathering, 



300 ELEMENTS OF INDUSTEIAL CHEMISTRY 

and method of expression. " Virgin oil," considered the best 
quality for edible purposes, is obtained from the hand-picked 
fruit, by crushing in such a manner as not to break the kernel. 
The pulp is then treated with water and pressed again. By this 
process salad oils are obtained. The pulp is then removed from 
the press, treated with hot water and again subjected to hydraulic 
pressure, the oil obtained being employed for lubricating, soap 
making, and for other technical purposes. The final expression 
comes into the market as " olive oil foots," extensively employed 
in the manufacture of " castile " soap. 

The best quality of the oil is greenish yellow. The consistency 
is that of a limpid oil at ordinary temperatures and beginning to 
deposit " stearin " below 10° C. The oil is valued more par- 
ticularly on its flavor. The finest edible oil has practically no 
smell and very little taste, but with inferior grades there is a 
distinct odor and the taste becomes sharp and uupleasant, due in 
part to increasing proportions of free fatty acids. The best edible 
oil contains only 0.3-0.5 per cent of free fatty acids, and anything 
much exceeding this precludes its use as a salad oil. The acidity 
is sometimes removed by treatment with alkali, and oils treated 
in this way do not show the absorption bands of chlorophyll which 
are often clearly given by the fresh oil. 

Olive Kernel Oil. This oil is obtained by pressing or extracting 
the seeds from olive stones. The cold-pressed oil is golden yellow 
in color, while the hot-pressed oil has a greenish cast. The 
extracted oil is dark green in color, probably due to the presence 
of chlorophyll. This oil in a way is the by-product in the manu- 
facture of olive oil, and resembles it very closely in all of its 
properties. 

ANIMAL OILS. These oils are obtained by heating the fatty 
matter with live or dry steam in open kettles or closed digesters; 
the old method of heating over the open fire is now used but infre- 
quently. One of the most modern processes consists in heating 
the stock with water, at a pressure sufficiently high to cause a 
complete separation, but not high enough to decompose the stock. 
When this " rendering " is complete the contents of the digester 
is filtered to remove solid matter, and the liquid portion allowed 
to stand so that the oil may rise to the top. The liquid portion 
remaining after the oil has been removed may be used again, 
or may be concentrated for use in glue stock. The solid matter 
is usually dried and sold for use in fertilizers. In some forms 
of rendering tanks the oil is allowed to rise to the top, where it 



OILS, FATS AND WAXES 



301 



is removed by tap valves along the side. The oil obtained by the 
above methods is usually sufficiently pure for commercial pur- 
poses. If it is to be used for edible purposes, it is customary to 
purify it further by bleaching. This is accomplished by passing 
the oil or fat through bone-black or fuller's earth. 
Animal oils may be divided into two classes: 



1. Marine animal oils. 



2. Terrestrial animal oils. 



MARINE ANIMAL OILS. The marine animal oils are char- 
acterized by their high iodine values, which in a way resemble 
the vegetable drying oils. As with vegetable oils, we have a 
gradual lowering of the iodine value through drying, semi-dry- 
ing, and non-drying oils, until we approach the constitution of 
the terrestrial animal oils. The members of this class of oils are 
liquids at the ordinary temperature, and will be considered 
under the three following groups: 

Fish oils Liver oils Blubber oils 

FISH OILS. The fish oils are obtained from various parts of 
the body of such fish as menhaden, herring, sardine, salmon, etc. 
The fish, or oily portion, is placed in rendering tanks, boiled and 
the oil drawn off from the top. The soluble portion is used for 
making fish glue, isinglass, and the solid portions sold as a fertil- 
izer under the name of fish scrap. 



TABLE OF CONSTANTS FOR SOME COMMON FISH OILS 



Name of Oil. 


Specific Gravity. 


Saponi- 
fication 
Value. 


Iodine 
Value. 


Refractive Index. 


Menhaden 

Sardine 

Salmon 


0.927-0.933 

0.933 

0.9258 


15.5° C 
15° C 

15.5° C 


190.6 

182 '8 


139-180 

161-193 

161.4 


1.480 
1.479 


15° C 
15° C 



Menhaden Oil. This oil is prepared from the body of the fish, 
which in appearance resembles herring, although it is somewhat 
larger. The time of fishing for menhaden is determined, of course, 
by the habits of the fish. Since they appear in northern waters 
in April and disappear in November, the fishing season is limited 
to those months. As one goes farther south, the season is 
lengthened ; in the Carolinas the boats are not put out of commis- 



302 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



sion until the latter part of December, though fishing does not 
begin much earlier there than in the northern regions. In the 
southern region, the spring and fall fishing furnishes most of the 
raw material, there being a dull season in midsummer, when 
catches are rare and unimportant. In Florida waters the fish 
are present throughout the winter. 

Sardine Oil. This oil is obtained in the preparation of canned 
sardines. It is also made on a large scale in Japan by chopping 
the fish and subjecting them to boiling and pressing. 

Salmon Oil. This oil is obtained on a large scale as a by- 
product in the canning industry of British Columbia. It is of 
a pale golden yellow color, with very little odor, and not unpleas- 
ant taste. 

LIVER OILS. As the name implies, these oils are obtained 
from the liver of various species of fish. They form a natural 
group which is characterized by the large amount of cholesterol, 
and biliary substances present in them. The iodine values bring 
them between the fish and blubber oils. 



CONSTANTS FOR LIVER OILS 



Name of Oil. 


Specific Gravity. 


Saponifi- 
cation 
Value. 


Iodine 
Value. 


Refractive Index. 


Cod liver 

Haddock liver. . 


0.9210-70 

0.9298 

0.9163 


15° C 
15° C 
15° C 


171-189 

188.8 

161 


167 
154.2 

114.6 


1.4800-52 


15° C 


Shark liver .... 













Cod Liver Oil. There are many grades of cod liver oil on the 
market, obtained in various ways from the liver of the codfish. 
The purest form of oil for medicinal purposes is that prepared 
from fish which are brought ashore alive. The fivers are heated 
in jacketed kettles, the resulting oil being known as " steamed 
liver oil." When it is impossible to bring in the live fish, they 
are opened and the livers collected. Provided no decomposition 
has taken place the oil obtained from this stock is known as 
" pale cod liver oil " and is used to some extent for pharmaceutical 
purposes. As often happens these livers are landed in a more 
or less putrid condition, so that the oil from them becomes unfit 
for medicinal use, and is known as " light brown oil." Should 
the product become very putrid the resulting oil is known as 



OILS, FATS AND WAXES 



303 



" brown oil." The oil not suitable for medicinal purposes is used 
in the currying of leather under the name of " cod oil." 

What is known as dark tank cod oil comes from Newfound- 
land and has a specific gravity of .9296; an iodine number of 129; 
fatty acid content 14 per cent and saponification number 190. 
Dark tank cod oil is made from cod fivers and is used for tanning. 
Cod liver oil contains quite an amount of stearine, which, to 
a great extent, settles out on standing. Oils which have been 
freed from stearine are known as " raked " oils. 

Shark Liver Oil. This oil is used to some extent as an adul- 
terant of cod liver oil; it is obtained in a manner very similar 
to that employed for cod oil. It is also used in the leather 
industry. The oil appears on the market as " yellow strained," 
" red," " vellow," " yellow red," " Japanese," " crude," and 
"refined." 

Haddock Liver Oil. The oil from haddock liver closely 
resembles cod liver oil, to which it is added to quite an extent 
as an adulterant. 

BLUBBER OILS. Under this heading will be included those 
oils obtained irom the blubber of various fish. They differ from 
each other quite widely in their chemical composition. 

CONSTANTS OF SOME BLUBBER OILS 



Name of Oil. 


Specific Gravity. 


Saponification 
Value. 


Iodine 
Value. 


Seal 

Whale 


0.9155-63 
0.9180- 

0.9300 

0.9180 

0.9258 


15° C 
15.5° C 

15° C 
15° C 


189-196 

188 

197.3 
195 


127-145 
115-155 


Dolphin 

Porpoise 


99.5 



Seal Oil. This oil is obtained from the blubber of the seal. 
It varies in quality, depending upon the method of extraction 
and the length of time the oil has been left in contact with the 
animal tissue. The following brands appear on the market; 
" water white," " straw seal," " yellow seal," and " brown 
seal." The last named oil is the result of long contact with 
animal matter and extraction at high temperatures. 

A white steam refined oil is produced only during the month 
of May in Newfoundland. It resembles whale oil but is not 



304 ELEMENTS OF INDUSTRIAL CHEMISTRY 

as " fishy." Its principal use is as a soap oil. Analytically 
seal oil resembles whale oil. 

Whale Oil. Formerly the whale blubber was worked up 
on board the whaler, but now it is generally brought into the 
" trying " station. The blubber is stripped from the flesh as 
completely as possible immediately when it arrives at the works. 
It is cut into strips, delivered to the melting pan, and boiled 
with steam. The best quality of the oil is of a very pale yellow 
color, and is known in the trade as " whale oil, No. 0." The 
fishy odor is relatively very slight. On further heating, the 
next N quality , " whale oil No. 1," is obtained, which is a little 
darker in color, and has more of a fishy odor than No. 0. 
Bleached No. 1 oil is sometimes sold as No. 0. The residue in 
the pan, together with the flesh of the whale, is heated in a digester 
under pressure of about 50 lbs. to the square inch. In this 
way " whale oil No. 2 " is obtained, which is of a brown color 
and strong fishy odor. When the bones are worked up, an 
oil is obtained known as " whale oil No. 3." This oil is darker 
than No. 2 and has a very strong odor. From the flesh which 
has undergone putrefaction " whale oil No. 4 " is obtained. 
This is still darker in color and has a very objectionable 
odor. 

Nos. 2, 3, and 4 are graded by color. 

No. 1 is pale yellow. No. 2 is orange. No. 3 oil in the crude 
state may be likened to coffee containing cream. No. 4 oil is 
practically a black oil. 

About 60 per cent of the total oil from whale is the No. 1 
grade. Thirty per cent is the No. 2 grade and the remainder 
is Nos. 3 and 4. No. does not appear on the market in material 
quantities. In this country No. 1 whale oil is frequently sold 
with an acid guaranty of not over 2 per cent. The No. 2 oil 
should not contain more than about 5 per cent of free fatty acid. 
No. 3 will run up to 15 per cent or so of fatty acid. The specific 
gravity of fish and whale oils ranges from .918 to .930. The 
iodine number of crude whale oil is very variable and ranges 
between 115 and 155 for all classes of these oils. 

In the pressing of whale oil to secure products of the proper 
cold test, a quantity of so-called stearine is obtained which is 
used mainly in the preparation of whale oil soap and for making 
railway coach lubricants. 

No. 1 filtered whale oil has a flash point, 570° F. and burning 
point 640° F. The viscosity at 100° F. is 166 seconds in the 



OILS, FATS AND WAXES 305 

Saybolt instrument. No. 3 filtered whale oil has a flash point 
of about 380° F. and burning point of 424° F. 

The maximum production of whale oil is about 60,000 bar- 
rels annually, this being obtained mostly in Canada, especially 
along the Canadian Pacific coast. Only a small proportion 
comes from the American Pacific coast. A very small and 
uncertain supply is derived from the Eastern coast, but the 
whaling industry which formerly made New Bedford an im- 
portant port no longer exists and the industry is at its height 
now along the Canadian Pacific shores. 

A small amount of sea elephant oil is brought into this 
country, but is usually sold as whale oil. 

The uses of whale oil are confined largely to the following: 

For hydrogenation purposes to produce edible products and 
fats suitable* for soap making; for tempering. It is not used 
in tanning to any great extent in this country, although it finds 
favor for this purpose in Germany. The water white and pale 
brands of whale oil are used for burning and for soap making, 
the brown quality being used for leather dressings. 

Dolphin Oil. The oil obtained from the blubber of the 
black fish, in its chemical composition is intermediate between 
whale oil, a glyceride, and sperm oil, a wax. There are two 
varieties of this oil, body oil and jaw oil. Both are of a pale 
yellow color, and contain large amounts of glycerides of volatile 
fatty acids. It is used for lubricating fine machinery, such as 
watches and other delicate instruments. On standing sperma- 
ceti deposits. 

Porpoise Oil. This oil is obtained by boiling the entire 
tissue of the brown porpoise. It is of a pale yellow color, and 
consists of the glycerides of valeric, palmitic, stearic, and oleic 
acids. There are two varieties of the oil, body oil and jaw oil. 
It is used as a lubricant for delicate machines. 

Terrestrial Animal Oils. The oils of this class have a 
low iodine number, and therefore belong to the non-drying 
oils. 

Sheep's Foot Oil. This oil is obtained from the feet of sheep 
in very much the same manner as described for neat's foot oil, 
it being similar to neat's foot oil, and is usually sold as such. 

Horse's Foot Oil. As a rule this oil is never placed on the 
market under its true name, but is usually mixed with sheep's 
foot or neat's foot oil. What is sold as horse oil is the liquid 
portion of horse fat. 



306 ELEMENTS OF INDUSTRIAL CHEMISTRY 

CONSTANTS FOR TERRESTRIAL ANIMAL OILS 



Name of Oil. 



Sheep's foot, 
Horse's foot. 
Neat's foot . 

Egg 

Lard oil ... . 
Tallow oil . . 



Specific C 


rravity. 


0.9175 


15° C 


0.913-27 


15° C 


0.914-16 


15° C 


0.9144 


15° C 


0.916 


15° C 


0.794 


100° C 



Saponification 
Value. 



194.7 

195.9 

194 3 

184.4-190 

193 



Iodine Value 



74.2 

73.8-90 

69.3-70.4 

68.5-81.6 

73 
55.8-56.7 



Refractive Index. 



1.4713 



25° C 



Neat's Foot Oil. This oil is obtained by boiling the feet of 
cattle with water. It is of a pale yellow color and free from 
odor. The commercial product usually contains small amounts 
of sheep's foot and horses' foot oils. On account of the high 
price of neat's foot oil, it is often adulterated with vegetable, 
fish, or even mineral oils. The most common adulterants are 
rape oil, cotton seed oil, corn oil, menhaden or other fish oils, 
and mineral oil. True neat's foot oil is an excellent lubricating 
oil, but its chief application is in leather manufactuie. 

Egg Oil. This oil may be obtained by pressure or extraction 
from the hard boiled yolk of hens' eggs. The pressed oil has a 
yellow color, while the extracted oil is of an orange shade. The 
nature of the solvent largely influences the properties of the 
oil obtained; those most commonly used being ether and petro- 
leum ether. In the form of egg-yolk it has very valuable prop- 
erties in certain tanning operations. 

Lard Oil. This oil is obtained by subjecting lard to hydraulic 
pressure. It consists in the main of olein with a small pro- 
portion of the glycerides of solid fatty acids, chiefly palmitic 
acid. The quality of the oil varies greatly according to the 
pressure and temperature maintained; hence, the constants 
will vary within a considerable range. Its principal use is as 
a lubricant and in cutting oils. 

Tallow Oil. This oil is the fluid portion which is separated 
on subjecting tallow to expression. The processes of manu- 
facture and the properties of this oil are similar to lard oil. It 
also resembles neat's foot oil, but contains a larger proportion 
of saturated glycerides and is regarded as less valuable as a 
lubricant. 

Vegetable Fats. To this class of fats belong those which 
remain solid at the ordinary temperature. They differ, however, 



OILS, FATS AND WAXES 



307 



very greatly in consistency, ranging from soft to very hard. 
This variation in hardness is dependent upon the amount of 
glycerides of oleic and linoleic acids present; the smaller the 
amount of these glycerides the harder the fat. 



CONSTANTS FOR VEGETABLE FATS 



Name of Fat. 



Cotton seed stearine. 
Palm oil 



Vegetable tallow 
Cocoa butter. . . . 



Palm kernel oil. 
Gocoanut oil. . . 
Japan wax 



Shea butter. 



Specific Gravity. 



0.9188- 
0.9230 

0.921- 
0.9245 

0.918 

0.9500- 
0.976 

0.9520 

0.9115 

. 9700- 
0.9800 



15° C 

15° C 

15° C 
15° C 

15° C 

40° C, 
15° C 



Saponifica- 
tion Value. 



195 

192-202 

200.3 
193.5 

242-250 

246-260 

217-237.5 

180-190 



Iodine 
Value. 



90-103 

51.5 

28-37 
32-41 

13-14 
8-9.5 
4.9-9.5 

57-63 



Refractive Index. 



1.4510 



1.4496 

1.4431 
1.4410 



60° C 



60° C 

60° C 
60° C 



Cotton Seed Stearine. This product is manufactured on a 
very large scale by cooling cotton seed oil, and collecting the 
resulting solid which separates out. It is of a light golden color, 
of about the consistency of butter, for which it is used as an 
adulterant and it is also used in making margarine. It has 
also been employed as a lard substitute. 

Palm Oil. Until recently, the only source of this oil was from 
the coast of Africa, but at present considerable quantities come 
from the Philippines. The oil is obtained from the fleshy part 
of the fruit of the palm tree. The process of making this oil is 
very crude. Either the fruit is stored in holes in the ground, 
when by fermentation the oil separates and rises to the top; 
or the oil is pressed out by hand. The kernels are not destroyed, 
and from them palm nut oil is obtained. The fresh oil has a 
deep orange yellov T tint not destroyed by saponification, a sweet- 
ish taste and an odor of orris root or violet, which is also imparted 
to soap made from it. The methods by which the natives obtain 
the oil are crude and depend upon a fermentation or putrefaction. 
Large quantities are said to be wasted because of this fact. The 
oil contains impurities in the form of fermentable fiber and al- 
buminous matter, and consequently develops free fatty acid 



308 ELEMENTS OF INDUSTRIAL CHEMISTRY 

rapidly. Samples tested for free acid have been found to have 
hydrolized completely and it is seldom one obtains an oil with 
low acid content. Because of this high percentage of free fatty 
acid, the glycerine yield is small, though the neutral oil should 
produce approximately 12 per cent of glycerine. 

Since soap made from palm oil is colored orange, bleaching 
before saponification is usually required. 

Vegetable Tallow. From the fruit of the Chinese tallow tree 
is obtained a hard fat. The fruit is steamed in perforated vessels, 
in which the fat melts and is ran off. The remaining seeds are 
then pressed and " Stillingia oil " obtained. Another process 
is also employed in which the whole fruit is crushed and pressed, 
thus yielding a mixture of vegetable tallow and Stillingia 
oil. 

Cocoa Butter. The cocoa beans are roasted, ground, treated 
with sodium carbonate and hot pressed. When freshly prepared 
cocoa butter has a yellowish color, but it turns white on standing. 
It has a pleasant odor and agreeable taste, and is less likely 
than almost any other fat to go rancid. It is used in confec- 
tionery, medicine, toilet creams and soaps. 

Palm Kernel Oil. This oil, as indicated above, is obtained 
from the kernels of the palm tree fruit. After the fleshy part 
of the fruit is removed the kernels are collected, screened, ground 
to a pulp and subjected to hydraulic pressure. It is a white oil, 
and when fresh has a pleasant odor and nutty taste. It is used 
very largely for soap making, and in the pure condition it is 
employed for edible purposes. 

" Stearin " from palm kernel oil is produced commercially of 
a somewhat higher melting point than that from cocoanut oil, 
and the " olein " may have a lower melting point than that of 
cocoanut " olein.'* There has been a prevailing belief that the 
keeping properties of palm kernel products were not as good as 
those of cocoanut oil, but owing to improved methods of refin- 
ing, this difference no longer exists. 

Cocoanut Oil. The source of this oil is the fruit of the Cocos 
nucifera (the ordinary cocoanut tree). The husk of the nut is 
removed by hand. The nut is split in two and is dried in the 
sun, which requires two or three days. The shell comes off soon 
after the drying has commenced. The dried meat is termed copra. 
Large quantities of copra are prepared by drying in kilns, but the 
color is usually darker when so treated. The copra generally 
is shipped and pressed at a place near the point of consump- 



OILS, FATS AND WAXES 309 

tion to avoid loss of oil by leakage in transit and to save the 
expense of containers. The oil is a solid, white fat at ordinary 
temperature, having a bland taste and the characteristic cocoa- 
nut odor. It is rarely adulterated and is very readily saponified. 
In recent years the price of this oil has increased materially 
because cocoanut oil is now being used extensively for edible 
purposes, especially in the making of oleomargarine and bakers' 
fats. Present indications are that shortly very little high grade 
oil will be employed for soap manufacture, since the demand 
for it in oleomargarine manufacture is steadily increasing and 
since new methods of refining the oil for this purpose are constantly 
being devised. 

The oil is found in the market under three different grades: 
(1) Cochin cocoanut oil, the choicest oil coming from Cochin 
(Malabar).* This product, being more carefully cultivated and 
refined than the other grades, is whiter, cleaner and contains a 
smaller percentage of free acid than the other grades. (2) Ceylon 
cocoanut oil, coming chiefly from Ceylon, is usually of a yellow- 
ish tint and more acrid in odor than Cochin oil. (3) Con- 
tinental cocoanut oil (copra). This product is generally superior 
to the Ceylon oil and may be used as a very satisfactory sub- 
stitute for Cochin oil, in soap making for example, provided it is 
low in free acid and of good color. 

Cocoanut oil has a saponification value of 246-260, an iodine 
value of 8-9.5 and the melting point is approximately 22° C. 
By pressing, cocoanut oil olein and stearin is prepared and the 
refined stearins are largely used as cocoa-butter substitutes in 
the manufacture of chocolate and biscuits, also for pharma- 
ceutical purposes. The refined olein finds use as a baking fat 
in biscuits and pastry. The whole oil is customarily used in 
making margarine. 

Shea Butter (Shea nut oil). This is a stiff, plastic fat some- 
what granular and occasionally of a " stringy " nature. It 
contains from 5 to 10 per cent of unsaponifiable matter. The 
refined fat, which can be rendered practically tasteless and 
odorless, finds an increasing use abroad for edible products. 

ANIMAL FATS. Under this head are included those solid 
fats which are derived from animal tissues. They vary in degree 
of hardness according to the amount of the glycerides of un- 
saturated fatty acids present, those with the higher amount 
being the softer. 

Although only non-drying fats will be considered it may be 



310 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



well to state that certain animal fats have quite pronounced 
drying qualities. 





CONSTANTS FOR ANIMAL 


FATS 






Name of Fat. 


Specific Gravity. 


Saponifica- 
tion Value. 


Iodine 
Value. 


Refractive Index. 


Horse 

Lard. . . 


0.9189 
0.934-0.938 
0.943-0.952 

0.937 
0.926-0.946 


15° C 
15° C 
15° C 
15° C 
15° C 


200.5 

193.5 

190.9 

193.2-200 

192-195.2 


81-2 
66-7 
46-55 
38-46 
35-46 


1.4510 
1.4510 




Beef tallow .... 
Mutton tallow. 
Butter 


60° C 
60° C 



Tallow is the name given to the fat extracted from the solid 
fat or " suet " of cattle, sheep or horses. The quality varies, 
depending upon the season, the food and age of the animal and 
the method of rendering. It comes to the market under the 
classification of edible and inedible, and is more specifically 
identified as beef tallow, mutton tallow or horse tallow. The 
better quality is nearly white and grows whiter upon exposure 
to air and light, though it usually has a slightly yellowish tint. 
It has a well-defined grain and clean odor. It consists chiefly of 
stearin, palmitin with some olein. Tallow is by far the most 
extensively used and important fat in the making of soap, but 
by means of the hydrogenation process, tallow-like products 
are now being made from vegetable oils as well as fish and whale 
oils, which are beginning to replace tallow in soap making. 

Beef Tallow. The fat from different parts of the animal are, 
as a rule, not kept separate during the rendering, except when the 
tallow is to be used in making oleomargarine. In this case selected 
fat is rendered at as low a temperature as possible. The oleo 
stock which is obtained is usually clarified, as by washing with 
weak brine. The oil is allowed to grain and is then pressed. 
The fat which is expressed sets to a soft buttery consistency and 
is known as oleo or oleo oil. The residue is in the form of hard 
cakes and is termed oleo stearin or beef stearin. In cold weather, 
when a more liquid oleo oil is required, the pressing is not as 
thorough, so that both products are softer and the yield of stearin 
is greater. All the other fatty portions of the animal are rendered 
to produce the maximum yield of fat. These form the various 
grades of tallow, most of which goes to the soap maker, but some 
of the better grades are employed for edible purposes. When 



OILS, FATS AND WAXES 311 

fresh, beef tallow is nearly white, odorless and almost tasteless, 
but the lower grades have a strong odor and flavor. A con- 
siderable quantity of tallow finds application in preparing lubri- 
cating greases, and leather dressings. 

Mutton Tallow. As a rule mutton tallow is harder than beet 
tallow, although in other respects it is very similar to it. The 
methods of rendering are about the same as for beef tallow. 
Mutton tallow tends to turn rancid on keeping, and hence is not 
often employed in butter substitute manufacture nor preferred 
in high grade toilet soaps. 

Horse Fats. When in a fresh condition horse fat is of a yellow- 
ish color, of a buttery consist ency, and neutral in reaction. On 
being allowed to stand for some time it separates into solid and 
liquid portions. It is now a commercial article owing to the 
large consumption of horse meat. In some localities it is used 
for edible purposes in place of lard; its chief use, however, is in 
the manufacture of soap. 

The bleaching of tallow is often practiced and fuller's eartn 
is useful for this purpose. The following procedure shows, the 
method employed. A quantity of tallow is melted and charged 
into the bleaching tank. The latter is steam jacketed and is 
provided with a mechanical agitator or a coil for stirring by com- 
pressed air. The tallow is heated to 82° C. and 10 lbs. of 
dry salt per ton of fat is added and thoroughly mixed by agitation. 
The salt coagulates any albumen and dehydrates the fat. The 
whole mass is allowed to settle for several hours. Any brine 
which has separated is drawn off from the bottom and the tem- 
perature of the fat then raised to 71° C. Fuller's earth to the 
extent of 5 per cent of the weight of the tallow is added and the 
whole mass agitated about thirty minutes. 

The bleached fat containing the earth is pumped directly 
to a previously heated filter press and the issuing clear oil may 
be run directly to the soap kettle. 

One of the difficulties experienced in the operation is the 
heating of the press to a temperature sufficient to prevent solidi- 
fication of the fat without raising the filter press to too great a 
temperature. To overcome this the first plate is heated by wet 
steam. Air delivered from a blower and heated by passage 
through a series of coils raised to a high temperature is then 
substituted for the steam. The moisture produced by the con- 
densation of the steam is reconverted to vapor by the hot air and 
is carried on gradually to each succeeding plate, where it condenses 



312 ELEMENTS OF INDUSTRIAL CHEMISTRY 

and again vaporizes. In this way a small quantity of water is 
carried through the entire press, raising its temperature to 
80°-100° C. This temperature is subsequently maintained by 
the passage of hot air. By this method of heating, the poor con- 
ductivity of hot air is overcome through the intermediary action 
of water vapor and the latent heat of steam is utilized to obtain 
the initial rise in temperature. The cake in the press is heated 
for some time after the filtration is complete to assist drainage. 
After such treatment the press cake should contain approximately 
15 per cent of fat. 

Lard. By rendering the fat which surrounds the kidneys and 
bowels of the pig a product is obtained known as " leaf lard." 
This, however, constitutes only a small portion of the product 
sold under this name. The following grades are recognized in 
the trade: Neutral lard No. 1, which is prepared by rendering 
the leaf in a fresh condition at a temperature of 50 ° C. This is 
used in the manufacture of " oleomargarine. " Neutral lard No. 2, 
which is obtained by rendering the back fat in the same way as 
No. 1. It is used by confectioners and biscuit makers. Leaf 
lard is obtained by subjecting the residue from neutral lard to 
steam heat under pressure. Choice kettle-rendered lard is pre- 
pared from the residue of neutral lard No. 1 by heating it, together 
with fat from the back, in steam-jacketed open kettles. Prime 
steam lard is the product obtained from other parts of the hog 
by rendering in tanks by direct application of steam. 

Lard is of a pure white color and has, at ordinary temperature, 
a salve-like consistence. It is often admixed with beef fat, beef 
stearin, cotton seed oil, cotton seed stearin, and other vegetable 
fats and the composition employed as a substitute for pure lard. 

Lard " compound " is made in enormous quantities by thick- 
ening edible cotton seed oil with oleo stearine so as to obtain a 
product of lard-like consistency. Stearin from other sources 
similarly may be used as a thickener or stiff ener and hydrogenated 
cotton seed oil or " vegetable stearin " is now being used for this 
purpose. 

Butter Fat. This product is obtained from the fat contained 
in cow's milk, and is used entirely for edible purposes. 

BUTTER SUBSTITUTES. The butter substitutes on the market 
consist of mixtures of animal fats and vegetable fats and oils. 
They are sometimes colored yellow with annatto or oil soluble 
yellow. More often no coloring agent is used, owing to the pure 
food law. The animal fats are oleomargarine, " oleo oil," or 



OILS, FATS AND WAXES 313 

neutral lard. The vegetable oils used are, generally, cotton seed 
oil and cotton seed stearine. Hydrogenated oils are beginning to 
be used. In the manufacture of oleomargarine the freshest 
materials are employed, great cleanliness being necessary. 
Methods of preparing the oil basis as well as the procedure of 
working this into oleomargarine vary considerably, but the fol- 
lowing will illustrate the character of the operation. Kidney 
fat is removed from the slaughtered animal as quickly as 
possible, carefully selected, washed with warm water, and 
thoroughly cleaned. This selected fat is then rapidly cooled, 
cut, shredded and ground in a roller mill. The fat thus 
disintegrated is placed in tin-lined steam-jacketed kettles and 
heated to 45° C, at which temperature a portion of the fat 
separates. The mass is clarified by sprinkling in salt and the 
liquid portion is run off into shallow tin-lined pans. On cooling 
the bulk of the stearine crystallizes. The cooled mass is then 
subjected to hydraulic pressure and oleo oil is collected. 

The oleo oil is churned with the vegetable oils and fats and 
with " pasteurized " skim milk. The object of churning is to over- 
come the tendency of the oleomargarine to crystallize. From 
the churn the margarine is run into cooling tanks, where it comes 
in contact with ice water. The solid mass thus obtained is worked 
in a kneading machine to remove the water, and it is here colored 
and salted to taste. Some manufacturers also add " butter 
flavor," which consists, for example, of a mixture of propionic 
acid, butyric acid and caproic acid or ethers. This also makes 
the margarine upon analysis appear more like pure butter. 

LIQUID WAXES. Sperm Oil. The most important member 
of this class is sperm oil, which is obtained from the head and 
blubber of the sperm whale. The head oil, which is the more 
valuable, when first separated is clear and limpid, but changes to 
a hard mass on standing. The body oil when fresh is of a light 
straw color. The two oils sometimes are mixed together and 
allowed to stand for two weeks before refining. The solid por- 
tion which separates is removed from the oil by subjecting to 
hydraulic pressure at 32° F., whereby a clear oil is obtained known 
as " winter sperm oil." The press cake is then warmed to about 
50° F., and again pressed, thus giving " spring sperm oil." The 
residue from the second pressing is allowed to stand for several 
days at a temperature of about 80° F. It is then subjected to 
hydraulic pressure, whereby " taut-sperm oil " is the result. 
The oils obtained from these three pressings vary in color from 



314 ELEMENTS OF INDUSTKIAL CHEMISTRY 

pale yellow for the refined oil to brown in the last named product. 
No. 1 sperm oil is a high grade of body oil and is very pale, almost 
water white in color. No. 2 sperm oil is darker and usually 
has an orange color. 

The specific gravity of sperm oil at 15° C. varies from 0.8799 
to 0.8835 (0.8820 being a fair average value), its saponification 
value from 125.2 to 132.6, and its iodine value from 81 to 90. 
It is used as a lubricating oil and in leather finishes. The extent 
of the latter use depends upon the price of lard oil. Sperm oil 
contains practically no glycerine. 

The term " spermaceti " is sometimes commercially used to 
refer either to the head oil containing spermaceti, or to the head 
oil with its content of spermaceti mixed with a certain amount 
of body oil. 

SOLID WAXES. Carnauba Wax. This is a very hard, 
sulphur-yellow, or yellowish-green substance, melting at about 
84°, of nearly the same specific gravity as water, and leaving 
on ignition a trifling quantity of ash, which often contains iron 
oxide. It is a wax which exudes from the leaves of the Corypha 
cerifera, a palm tree growing in Brazil and a few other South 
American countries. The white powdery mass which is scraped 
off from the sun-dried leaves is thrown into boiling water, thus 
melting the wax which collects as a solid mass on cooling. The 
crude product is dark in color, but on refining becomes much 
lighter. It has a specific gravity of from 0.990 to .0999, the sa- 
ponification value being from 79 to 95, and the iodine number 
about 13.5. When heated the wax gives off an agreeable aromatic 
odor. The principal use of carnauba wax is in floor waxes, polish- 
ing pastes and for raising the melting point of soft waxes. It is 
sometimes used in phonograph cylinders and for candlemaking. 

Japan Wax. This is a hard tallow-like mass which surrounds 
the kernels of the berries of several varieties of sumach trees 
found in China and the western provinces of Japan. The berries 
are collected and stored until they have fully matured, then are 
crushed and winnowed to separate the husks. The powdered 
mass so obtained is put into sacks and subjected to pressure. 
The berries yield from 15 to 25 per cent of a greenish, tallow- 
like mass which is refined by remelting and filtration. The wax 
is v bleached by exposure to sunlight, just as is done in the case of 
beeswax. Japan wax brought to this country is usually of a 
pale yellow color and although quite hard has a slightly sticky 
feel and possesses a characteristic odor. When the wax has been 



OILS, FATS AND WAXES 315 

kept for a long period it acquires a rancid smell. It is said that 
perilla oil is used as an adulterant. 

Japan wax consists chiefly of plamitine and free palmitic 
acid. The free fatty acids vary considerably, but range from 
4 to 12 per cent or higher. The specific gravity ranges from 0.975 
to 0.984. The saponification value is about 220 and the iodine 
number from 4 to 15. Being a glyceride Japan wax is readily 
distinguished from the true waxes by its saponification value 
and by yielding glycerine on saponification. The wax is some- 
times adulterated with a considerable proportion of water, ranging 
as high as 30 per cent. Its principal use is in floor waxes, as a 
constituent of various polishes and dressings and in finishing 
leather. 

Chinese Wax. This material, also known as insect wax, is 
a secretion of an insect inhabiting a variety of evergreen tree 
found in China. The wax is yellowish white in color and is nearly 
odorless and tasteless. It resembles spermaceti in appearance, 
but is considerably harder. Insect wax is used for making candles, 
for polishing purposes and as sizing for paper and cotton goods, 
but on account of its extensive use in China it does not find its 
way to our country to a large extent. 

Myrtle or Bayberry Wax. The wax is obtained by boiling the 
berries of various species of Myrica with water. The wax has 
a green color due to chlorophyll, but may be bleached on exposure 
to sunlight or air. The fatty acids of this waxy material consist 
chiefly of palmitic acid. The saponification value is 205 and the 
iodine number 2-4. The wax is prized for use in the manufac- 
ture of so-called bayberry tallow candles. 

Candelilla Wax. This wax is found coating the entire surface 
of a plant that grows wild in the semi-arid regions of northern 
Mexico and southern Texas. The plant is reported to be abun- 
dant over large areas of this section, where it occurs as bunches 
of leafless, reed-like stems 2 to 4 feet high and from one-fourth 
to one-half inch in diameter. The common name given to the 
plant by the Mexicans is candelilla. According to competent 
botanical authorities it is in all probability Euphorbia antisyphil- 
itica. The wax may be obtained by immersing the plant in 
boiling water, when the wax separates and rises to the surface. 
Obtained in this manner it is usually of a dark brown color due 
to the presence of minute fragments of bark or other foreign 
matter. When refined the wax is opaque to translucent and of 
a brownish-yellow color. The wax is harder than beeswax, but 



316 ELEMENTS OF INDUSTRIAL CHEMISTRY 

not as hard and brittle as carnauba wax. The specific gravity of 
the well refined wax is 983, melting point 67-68, saponification 
value 65, iodine number 37 and the refractive index 1.4555 at 
71.5° C. Candelilla, like carnauba wax, is used in polishing 
compositions and for raising the melting point of softer waxes. 

Wool Wax, Lanolin. In the scouring of wool, preparatory 
to spinning, a product called wool fat or wool wax is obtained. 
This is usually removed from the fleece with solvents. The 
crude product finds application in the currying of leather, while 
the, purified product "lanolin" is used in pharmaceutical prep- 
arations. The preparation of lanolin is a complicated operation 
and much secrecy is maintained with regard to the precise methods 
employed. 

Beeswax. This product is secreted by the honey bee, and 
serves as the material for building up the honeycomb. The comb 
is melted in hot water, strained to remove impurities, and sub- 
jected to hydraulic pressure. The press cake is boiled a second 
time and again pressed. Beeswax is of a yellow color, and 
practically tasteless. 

Spermaceti. This wax occurs in the head cavity and the 
blubber of the sperm whale. Its method of preparation is 
indicated under sperm oil, of which it constitutes the largest part 
of the solid portion. In the refined condition it forms white 
lustrous masses, is very brittle and can be easily rubbed into a 
powder. Its chief use is in the manufacture of candles. 

Shellac Wax. In bleaching shellac the raw lac is dissolved 
in aqueous alkali and a hard waxy material separates, which is 
much prized for use in polishing compositions and shoe black- 
ings. The wax resembles carnauba wax in polishing qualities. 
Shellac wax possesses a brown to yellow color and when heated 
gives off an odor suggestive of shellac. 

Montan Wax. By extraction of the lignites found in Saxony 
and Thuringia by means of volatile solvents, a waxy material 
known as montan wax is obtained. The crude wax is of a dark 
brown color, but by distillation with superheated steam a white 
or nearly white product melting above 70° C. is obtained. Mon- 
tan wax is finding a constantly increasing field of application as a 
substitute for carnauba wax. 



CHAPTER XV 
LUBRICATING OILS 

General Considerations. The object of lubrication is to 
diminish friction and thus conserve power. The shaft does not 
(or should not) come in contact with its box, but revolves on a 
thin film of lubricant. I like the conception of Southwick that 
the shaft rotates on the molecules of the oil, as it were upon the 
balls of a ball bearing. The resistance which the particles of 
tins film offer to being torn apart, or the shearing modulus as the 
engineer terms it, measures the efficiency of the lubricant em- 
ployed, consequently the cardinal principle underlying all lu- 
brication is to use the thinnest (or least viscous) oil that will stay 
in place and do the work. 

Another important consideration to be observed in choosing 
a lubricant is, that it should not absorb oxygen from the air, 
forming a gum which would increase the viscosity, or turn rancid, 
and attack the metals with which it is brought in contact. The 
liability to oxidize or gum can be shown by the gumming test, 
which also has been found to be a measure of the extent to which 
an oil will carbonize in a gas or gasoline-engine cylinder. Be- 
sides these two tests, which may be considered as measuring the 
efficiency of the oil, other tests are employed which either measure 
the safety, serve to identify the oil, or to determine if it be suit- 
able for the purpose for which it is intended. Such are the flash 
and fire tests, the evaporation test, the free acid test, and the 
test for thickeners or soap; while the specific gravity of a mineral 
oil, iodine, Maumene and saponification values of an organic 
oil serve either to identify it or indicate if it be adulterated. The 
cold test and friction test show its availability under conditions 
approximating that of use. 

Choice of Oils for Certain Purposes. An oil should 

be sufficiently fluid to flow readily between a journal and its bear- 
ing at the temperature of use, and not be forced out by the pres- 
sure under which it is running, or to which it is likely to be exposed. 
Any viscosity in excess of this means a needless waste of power. 

317 



318 ELEMENTS OF INDUSTRIAL CHEMISTRY 

The fact should not be overlooked that mineral oils lose their 
viscosity rapidly when heated, more so than the organic oils, 
and that the tendency of the latter is to increase the viscosity. 

A suitable lubricating oil should not gum or thicken on expo- 
sure to the air; it should not give off inflammable vapors below 
300° F., nor lose more than 4 per cent on exposure for a work- 
ing day at the temperature of the bearing upon which it is used. 
It should contain no acid to attack the bearing or shaft. It 
should have the least possible cohesion among its own particles 
and the greatest possible adhesion to the metals of which the 
shafts and bearings are composed. Petroleum oils fulfill the 
first condition and animal or vegetable oils the last. 

WATCH OIL. For oiling the most delicate machinery, as 
watches and clocks, the oil obtained from the dolphin, blackfish 
or " snuffer " is used. This exists in the cavities of the jaw and 
also in the brain or " melon " of the fish. It is rendered at a low 
heat, chilled and filtered at a low temperature, bleached and 
refined by sunning in contact with lead plates to remove acid. 
It is a pale yellow, very fluid oil of peculiar odor. 

SPINDLE OIL. This is the lightest and most fluid of the 
lubricating oils. The gravity varies from 27-35° Be., the flash 
from 320 to 430° F., the viscosity 30 to 400 seconds, Saybolt at 
70° F., and the evaporation test should not be over 4 per cent. 
From what has already been said, nowhere is the necessity for 
low viscosity greater than in the case of these spindle oils when 
the bearings are multiplied by thousands. A case is on record 
where the increase in the viscosity of the spindle oil stopped 
the engine and shut down the mill. Besides being used for 
spindles it is used for sewing machines, typewriters, etc. 

LOOM OIL. This is merely a heavy spindle oil. One which 
the writer tested had a gravity of 28°, flash 360° F., and viscosity 
of 203 seconds. Here, as in the case of spindle oils, the evapora- 
tion test should be low, as the hydrocarbon vapors formed have 
occasioned serious fires. 

ENGINE OILS. Engine oils are classed as light and heavy; 
besides being used for engines, as their name denotes, they find 
general employment for shafting, machinery, etc., about the mill 
or works. They are usually hydrocarbon oils of gravity 32-23°, 
flash 300 to 430° F., and viscosity from 50 to 400 seconds at 
70° F. Where the duty is heavy or the bearings are rough, 
they are sometimes mixed with animal oils, as lard or whale 
oils. 



LUBRICATING OILS 319 

CYLINDER OILS. Cylinder oils, or more accurately, steam 
cylinder oils, as the Germans call them, are divided into low and 
high pressure. Here a different problem has to be met, that of 
making the oil adhere to the surfaces of the piston and valves. 
This is accomplished by the addition of some fatty oil which 
adheres to the metals and the mineral oil adheres to it. The 
action of the fatty oils would seem to be analogous to that of a 
mordant in fixing dyes. Pure fatty oils, while they have been, 
and may now in some cases (with low pressures) be used, are 
open to the objection that these, being giycerides, are decomposed 
by high-pressure steam with the liberation of fatty acids which 
attack the iron of the cylinder, causing pitting and scoring. 

C 3 H5(St)3+3H 2 = C3H5(OH)3+3H St. 1 

On the other hand, when the condensed water from the exhaust 
steam is used as boiler-feed water, owing to the fact that these 
fatty oils emulsify so well with it, renders it necessary to use 
pure mineral oils. The cylinder stocks, that is, the pure petroleum 
bases, have the following characteristics: Gravity 23-28° Be., 
flash 500 to 630° F., viscosity 100 to 230 seconds at 212° F. It 
would seem hardly necessary to state that the low-pressure oil 
should have the lower of these figures. The viscosity of cylinder 
oils should be taken at the temperature corresponding to the 
pressure at which they are to be used. 

The fatty oils used are, degras, tallow, linseed, cotton seed, and 
blown rape, all as free from acid as possible and in quantities 
varying from 1 to 25 per cent. 

A lubricant which seems to promise unusually well for cylinders 
is an artificial deflocculated graphite suspended in water. This 
is so fine that it will go through the pores of the finest filter paper 
and it seems to fill the pores of the metal, ensuring tighter fitting 
piston rings and at the same time possesses little cohesion. 

GAS ENGINE OILS. Gas engine oils, particularly for the 
cylinders, should possess as their chief requisite, besides that of 
lubrication, the property of not carbonizing at the temperatures 
attained. The liability of carbonization seems to be intimately 
connected with the amount of tarry matter yielded in the gum- 
ming test. For automobiles the oils of the following character- 
istics have yielded good results: Flash 380-450° F. (covered 
tester), viscosity 180-185 seconds (at 100° F., Saybolt Universal)., 

1 St = Stearic acid = C17H35COOH. 



320 ELEMENTS OF INDUSTKIAL CHEMISTRY 

gumming tests very slight or slight. For large size gas engines 
probably a heavier oil would be required having these char- 
acteristics: Gravity 26-28° Be., flash 400-475° F., viscosity 250 
seconds at 70° F. 

GREASES. Gillett divides the greases into six classes: 

1. The tallow type, a mixture of tallow with palm-oil 
soap with some mineral oil; this was common twenty years 
ago. 

2. The soap-thickened mineral-oil type, a mixture of mineral 
oh\ usually with lime or sometimes soda soaps, the commonest 
type at present. 

3. Types 1 or 2 mixed with graphite, talc, or mica. 

4. The rosin-oil type, a mixture of rosin oil thickened with 
lime, or sometimes litharge, with mineral oil. They contain often 
20 to 30 per cent of water and are used as gear greases. They 
may contain also tar, pitch, ground wood or cork, and any of 
the fillers mentioned in 3. 

5. Non-fluid oils — oils or thin greases stiffened with " oil 
pulp " or " dope," i.e., aluminium oleate. 

6. Special greases with special fillers. 

These greases show a high coefficient of friction at first, 
causing a rise of temperature which melts the grease, producing 
the effect of an oil-lubricated bearing. The graphite greases 
show an unexpectedly low lubricating power; the rosin greases 
show a high friction at first, but after the bearing has warmed up 
compare well with the more expensive greases. The high mois- 
ture content would seem to have the advantage of making them 
less sticky. The line soap greases (Class 2) are not as good as 
the tallow greases (Class 1), and are inferior as lubricants to those 
compounded with soda soaps. 

BELT DRESSINGS. Where the object is the softening of the 
belt they are usually mixtures of solid fat, waxes, degras, or tallow 
with fish oils to make the belts cling; in some cases they are 
mixtures either of corn or cotton seed oils, which have been treated 
with sulpur chloride, with mineral oil and thinned with naphtha, 
or they may be mixture^ of the above fats with rosin or rosin oil. 
These are least desirable. Preparations containing wood tar are 
also used. 

Car Oils, Reduced Oils, Well Oil, Black Oils. These 

are commonly crude oils from which the more volatile portions, 
the naphthas, and, burning oils, have been removed by distillation. 
Some railroad specifications require a gravity of 29° Be., flash 



LUBRICATING OILS 321 

point 325° F., cold test 5 to 15° F., according to the season of use, 
and a viscosity 100 to 120 seconds at 70° F. 

Compressor and Ice-machine Oils. These are light 

spindle oils of a gravity of 26-27° Be., 60 to 100 seconds at 70° F., 
viscosity, 325-360° F., flash, and a cold test of to 4° F. 

CRANK-CASE OILS. These should emulsify but little with 
water, consequently should be pure mineral oils. Much seems to 
depend upon the water with winch the oil is mixed in the crank 
case, so it is difficult to predict how oils of practically the same 
constants will behave with different waters. An oil giving these 
figures has proved eminently satisfactory: Gravity 26-27° Be., 
flash 455° F. 3 viscosity 100° at 212° F. 

Milling Machine or Soluble Oils. These are usually 
lard, suiphonated oils, or mineral oils held in suspension by soaps 
or alkalies, as borax, sodium carbonate; the soaps are either 
ammonium, sodium, or potassium, with oleic, resin, or sulpho 
fatty acids. They should not appreciably attack the metals 
and should form a persistent emulsion. The U. S. Navy require- 
ments are that upon twenty-four hours' standing upon polished 
brass or copper it must not be turned green. German require- 
ments are that a steel plate, 30X30X3 mm. should not lose more 
than 18 mg. in a 1 or 2 per cent solution of the oil after lying for 
three weeks in it. 

NEUTRAL OIL. An oil without "bloom," of 32-36° Be., 
290-318° flashpoint and 47 to 81 seconds viscosity at 70° F. 

" OIL-DAG." This is the term applied by Acheson, the 
discoverer and maker of carborundum and artificial graphite to 
a colloidal suspension of pure deflocculated graphite in oil, so fine 
that it will go through the finest filter paper. Care must be 
taken that the oil is free from acid, whether mineral or organic, 
as this causes a precipitation of the graphite. A small quantity 
of " Oil-dag " in an automobile oil caused it to last for 700 miles 
instead of 200, the usual distance with one filling without the 
graphite. 

OlLLESS BEARINGS. These are wooden blocks, often of 
maple thoroughly impregnated with 35 to 40 per cent of grease, 
which replace metal journals; the grease may be a mixture 
of paraffine, myrtle, or beeswax with stearine, tallow, or vase- 
line. 

SCREW-CUTTING OILS. These are often mixtures of 27° Be. 
paraffine, and 25 per cent fatty oil, preferably cotton seed, 
although pure lard was formerly used. 



322 ELEMENTS OF INDUSTEIAL CHEMISTRY 

STAINLESS OILS. These are spindle or loom oils mixed 
with fatty oils — lard or neatsfoot; the fatty oil being more 
easily emulsified or possibly saponified in the scouring process, 
aids materially in washing out the mineral oil with which it is 
mixed. One type of these oils is compounded of 40 per cent 
neutral oil, 30 per cent cotton seed, 20 per cent olive, and 10 
per cent first-pressing castor. 

TRANSFORMER OILS. These should be either pure rosin or 
mineral oils and be free from water, acid, alkali, and sulphur. 
They may be freed from the first two impurities by treatment 
with sodium wire after the usual method of organic chemistry. 
They should not lose more than 0.2 per cent when exposed to 
100° C. for five hours, have a viscosity of about 400 seconds 
at 70° F., a flash of 340-380° F. and remain liquid at 32° F. 

TURBINE OIL. Steam turbines require a pure mineral oil 
of most excellent quality. As the oil is circulated around the 
bearings by a pump it should be of low viscosity and gravity 
and free from acid, mechanical impurities, and tendency to 
resinify; it should be low in sulphur contents. An oil of 30° 
Be., 150 seconds viscosity at 70° F., and 420° F. flash has given 
good results. 



CHAPTER XVI 
SOAP, SOAP POWDER AND GLYCERINE 

Theory of Soap-making. When tallow, lard, palm oil, 

corn oil or other fatty material is treated with a solution of sodium 
hydroxide or potassium hydroxide, a chemical change takes place, 
resulting in the formation of a product soluble in water, and 
possessing .properties entirely different from the original oil or 
fat employed. When the soluble product is treated with an 
acid the resulting body becomes insoluble. If this operation is 
conducted in a quantitative manner, it will be found that the 
insoluble substance obtained from the acid treatment is only 
about 90 per cent of the original weight of the fat. Something, 
therefore, has been eliminated during the operation. This may 
be recovered from the acid liquor by evaporation, and is found 
to possess a sweet taste, an oily consistency, and is known as 
glycerine. The insoluble portion recovered above has an acid 
reaction, when combined with alkali is soluble, and upon inves- 
tigation proves to be made up principally of such compounds 
as stearic, palmitic and oleic acids. Thus we draw the con- 
clusion that fats are glycerides of fatty acids; and that in soap- 
making the caustic alkali decomposes the fatty glycerides with 
the formation of salts of the fatty acids known as soap, and 
the separation of glycerine. 

In boiled soaps this glycerine is separated, while in half- 
boiled or cold-made soaps it is not, and remains a part of the 
soap. 

This reaction is indicated in the following equation: 

C17H35COOCH2 NaOH Ci 7 H 35 COONa CH 2 OH 

I I 

Ci 7 H 3 5COOCH 2 -|-NaOH = Ci7H35COONa-|-CHOH 

I I 

C17H35COOCH2 NaOH Ci 7 H 35 COONa CH 2 OH 

Glyceryl stearate in Caustic Sodium stearate Glycerol 

tallow soda (Soap) (Glycerine) 

323 



324 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



Although there are many substitutes for tallow which are 
employed in soap-making, they all require an alkali for saponifi- 
cation and all act in the manner above described. There are, 
however, some substances, such as rosin, which, when used in 
the production of soap, the action as stated above is modified. 
Rosin is an acid and unites directly with the caustic soda to 
make a salt. 

Classification of Soaps. Soaps are divided into two 

principal classes, namely: hard soaps and soft soaps. In the 
former caustic soda is employed and in the latter caustic potash 
is used. The term soda soap and potash soap are also some- 
times used to distinguish the two classes. Further, depending 
upon the method of manufacture, we have boiled soaps, half- 
boiled soaps, and cold-process soaps. Hard soaps are of various 
kinds, such as castile, curd, mottled, yellow, and transparent. 

Soft soaps come on the market as 
a paste or in a semi-liquid condi- 
tion. In some soaps both caustic 
soda and caustic potash are used in 
their preparation. 

As soap is used for a great va- 
riety of purposes, its preparation 
must necessarily vary. The choice 
of stock depends upon whether a 
high-grade soap is to be made,' in 
which the choicest materials must 
be selected, or whether a cheap soap 
is to be manufactured. Soap is 
used very largely in the textile and 
leather industries, and should be 
specially prepared for the purpose 
to which it is to be put. 

Boiled Laundry Soap. The 
melted fat and oil is pumped into 
the soap kettle (Fig. 100) from the 
storage tanks and with it a small 
stream of 18° caustic soda lye is 
run in from a separate line. Enough 
steam is turned on to keep the con- 
tents well mixed. The union of the 
fat and caustic soda sets up quite a little " heat of reaction " 
and very soon the steam may be eased off. As much boiling 




Fig. 100. 



SOAP, SOAP POWDER AND GLYCERINE 325 

room as bossible is saved for finishing the saponification. The 
lye is kept slightly behind the stock until the fat is all pumped 
up. An excess of caustic can be determined by rubbing a 
sample taken from the kettle between the fingers until cool; 
a sharp taste denotes an excess of caustic. Toward the end of 
the saponification, the soap begins to take on a darker color, 
become smooth and assume a high gloss. A sample taken on 
a small flat piece of wood, called a paddle, is now quite trans- 
parent and rolls off the paddle in sheets. The lye must now be 
added in small lots with frequent testing as described below. 
An alkalinity not over .20 per cent is very desirable and a 
kettle which holds this alkalinity after three boilings and tests 
may be considered as finished for this change. 

GRAINING. The soap must now be separated from the free 
glycerine and is done by adding salt, in which solution the soap 
is insoluble. This is called " graining." The kettle is well 
boiled, dry salt shoveled in or a brine (salt) solution is run in 
and mixed through by boiling until a sample on a paddle shows 
the soap in a broad flat curd from which the lye runs freely. 
The steam is shut off, the soap rising to the top of the kettle 
and the salt solution containing the glycerine settles out on 
the bottom. 

SECOND CHANGE. The lye from the first change is drawn 
off from the bottom into an empty kettle until soap appears 
and then shut off. The soap is boiled up, a dash of 18° Be. 
caustic soda added and after being well boiled through, the 
alkalinity is tested. If an excess of .20 per cent is not shown, 
more caustic is run in, boiled, and tested until the soap holds 
this alkalinity. Water is now added until the soap shows, 
after boiling through, a smooth appearance. This is called 
"flattening out." When the water is all in, the graining is re- 
peated as before. 

ROSIN SAPONIFICATION. A straight tallow soap is rather 
slow in lathering and needs a softening agent, such as oil or 
rosin to increase its solubility. In toilet soaps oil is used and 
in laundry soap rosin. The rosin is incorporated in two ways, 
either by direct saponification in the same kettle as the first 
change was made, or by a separate saponification in another 
kettle and a subsequent incorporation. 

Direct Saponification. The first change soap after all the 
wash changes have been made and last lye drawn is boiled up, 
a little salt, any scrap or broken soap added and enough 35 to 



326 ELEMENTS OF INDUSTRIAL CHEMISTRY 

30° caustic lye run in to " open " or grain the soap. While the 
kettle is slowly boiling, the rosin, cracked up in small lumps, 
is shoveled in. From time to time samples taken from the boil- 
ing soap are tested for alkalinity, and if not up to .2 to .3 per cent, 
enough caustic is added to bring it up to the mark. While the 
rosin is being saponified in this way, a " second rosin " lye from 
another kettle is pumped in and its caustic content assists in dis- 
solving the rosin. An excess of caustic lye must at all times be 
present in this change, as no salt is to be added for graining, the 
free caustic doing this graining. This is the only lye which is 
run' away to the sewer when settled and it contains nearly all 
the soluble impurities. When the rosin is all in and the final 
test for free caustic made, the soap is allowed to settle, generally 
over night, so as to get out into the lye as much color and impurity 
as possible. 

Saponified Rosin. Water and soda ash (Na2COs) are 
boiled in a kettle to make a 12° Be. solution. One thousand 
pounds of rosin require 150 pounds of ash. The solution is kept 
slowly boiling while the rosin is shoveled in, and the solution of the 
rosin completed by frequent short boilings. It is finished when 
no more rosin is found floating on the surface after the boiling 
and settling. Just before it is pumped out of the kettle onto the 
tallow soap enough dry salt is added to make it pump well. The 
incorporation with the tallow soap proceeds the same as with 
the direct rosin saponification except that less caustic soda is 
used. 

SECOND ROSIN CHANGE. When the first lye has been drawn, 
the soap is brought to a boil and enough 25-30° caustic soda run 
in to make an alkalinity of 3-4 per cent and continued boiling 
while a boiled up nigre of a previous boil is pumped in to fill up 
the kettle. The main object of this change is to insure a com- 
plete saponification of the rosin. 

STRONG CHANGE. When the second rosin lye is off, the 
soap is boiled up and enough water or 4-5° caustic lye is added 
to smooth or flatten out the soap and get it into a condition to 
drop or settle out the excess caustic with the other alkaline 
impurities. 

FINISH. After a few hours, the soap will drop a heavy, 
slimy lye which is drawn off and the soap boiled up. # Experience 
alone now dictates the procedure. If the soap is thick (heavy), 
a little water is run in it and boiled through, which leaves the 
soap as it boils in a smooth, high-polished condition, and when 



SOAP, SOAP POWDER AND GLYCERINE 



327 



the steam is shut off the process of settling or clarification can 
readily be seen at once on the surface. 

SETTLING. The soap should stand about a week to be well 
settled. During the settling the soap separates into two layers, 
the upper part being the good soap, i.e., a soap containing but 
traces or a small amount of free alkali and about 31-32 per cent 
of water, which seems to be the amount of water needed to make 
a good settled soap, a sort of water of constitution, and a lower 
layer or " nigre " which is a soap with a large amount (55-70 per 
cent) of water, free alkali and any other alkaline impurities 
(Na 2 S04+NaCl) present. The purpose of the last change is 
to manipulate the soap, so as to concentrate these impurities in 
the nigre. 

CRUTCH-ING. After settling, the soap is pumped out of the 
kettle through the leg as shown in Fig. 100. The " crutcher " is 
a mixing-machine which derives 
its name from the early soap 
factories. This mixing was then 
done by hand with a wooden 
stick shaped like a crutch. The 
" crutcher " (Fig. 101) is sur- 
rounded by a jacket into which 
either steam for heating or water 
for cooling is introduced. It has 
an Archhnedean screw for the 
stirring and in the center a cy- 
linder over which the soap passes 
during the agitation. Any ma- 
terial such as sodium carbonate, 
sodium silicate, borax, starch, 
talc, grit or perfume can thus be 
incorporated into the soap. All 
laundry soaps carry some such 
rilling, which is by no means an 
adulteration and needs no apology for being present. The tem- 
perature at which the soap is dropped is carefully controlled in each 
crutcherful and regulated by introducing either steam or water to 
the jacket. Good results are obtained by keeping this heat about 
140-144° F. When thoroughly mixed the soap, still semi-liquid, 
is dropped out of the bottom of the crutcher into frames. The 
pump is shut off when the nigre is reached and the nigre boiled 
up to be pumped out into a second rosin change. 




Fig. 101. 



328 ELEMENTS OF INDUSTRIAL CHEMISTRY 

FRAMING. These "frames " are tight boxes supported on a 

truck (Fig. 102) and hold one entire charge from the crutcher. 
The sides are bolted together in such a manner that they may 
be easily taken off when the soap is hard enough. This is called 
" stripping." The time of " stripping " depends on the season 
— three days in winter and four days in summer. The soap 




should be stripped as soon as possible, as the soap cuts better 
when cool. With soap of good body, the cutting may be done 
the next day. 

SLABBING AND CUTTING. When the soap is hard enough, 
it is run through the " slabber " (Fig. 103). This is a machine 
with a cutting-head large enough to slab the whole frame at once. 
The cutting-head has wires drawn across it at spaces equal to 
the thickness of a cake of soap. Each slab is now put through 
the " cutting-machine " (Fig. 104) and given two cuts, one through 
its length and the other at right angles to it, which turns out the 
slab completely cut into cakes. In the power cutting machines 
of latest type the cut cakes fall, spaced, onto a rack which is 
lifted from the table and placed on a truck for transportation 
to the drying-room, which may be done artificially or allowed to 
stand in well-ventilated rooms. 

PRESSING AND WRAPPING. The soap stands on these racks 
until the surface dries over enough so that it may be handled 
and pressed without marring it. This is called " skinning over." 



SOAP, SOAP POWDER AND GLYCERINE 



329 



Green or fresh soap acts very badly in the presses and is easily 
dented in passing to the wrapping-machines (Fig. 105), which 

run QiifrmiQfi'pQllv ar-irl nronoroC! +V10 arvan fr»T» +V10 hnvpa 



ted in passing to the wrapping-machines (Fig. '. 
automatically and prepares the soap for the boxes. 




Fig. 103. 




Fig. 104. 



THE TWITCHELL PROCESS. This process is a newer method 
employed in some soap factories for a treatment of the stock 



330 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



before soap-making, and has for its object a separation of the 
fat or oil into fatty acid and glycerine before it reaches the soap- 
kettle. It can be readily seen that the operation of making 
soap is then easier in the earlier or " killing " changes and re- 
moves the " salting-out " of soap in these earlier changes entirely, 
as there is no glycerine to wash out. 

Method. The fat or oil is first purified by steaming with 
about 1 per cent 60° H2SO4 for about two hours, after which 
the acid, impurities, and water of condensation are drawn 




Fig. 105, 



off. The melted and purified fat is run into a wooden tank, 
closely covered to exclude air. After heating up, 1 per cent 
of the " Twitchell Reagent " (sulpho-benzene stearic acid, 
C6H4HSO3C17H35COO) is added and the whole mass steamed 
for twenty-four hours with the addition from time to time of 
small amounts of H 2 S04< After settling, the glycerine water 
(15 per cent glycerine) is drawn off, neutralized with lime and 
evaporated to a " crude glycerine " of 88-90 per cent glycerine 
content. 

After the glycerine water is drawn off, the fatty acids are 
boiled with water and a small amount of lime, to remove all 
the soluble acids, air likewise being carefully excluded. After 



SOAP, SOAP POWDER AND GLYCERINE 331 

this neutralization is complete, the fatty acids may then be 
stored in wooden tanks until ready for use. 

The advantages of the " Twitchell " process are: 

a. A larger yield of glycerine. 

b. A purer and stronger crude glycerine. 

c. A means of making rosin soaps in a crutcher without 

boiling the fat. 

a. By changing the stock into fatty acid and glycerine before 
the actual soap-making is begun, an opportunity is afforded to 
entirely free the stock of its glycerine without the use of salt. 

b. The crude glycerine obtained from soap lyes, called " soap 
lye crude,'" contains from 80 to 84 per cent of glycerol and from 
7 to 10 per cent of salt. The crude obtained from the " Twitchell 
process," called " saponification or candle crude" carries from 
88 to 90 per cent glycerol and only traces of salt. Salt is the 
worst part of the glycerine recovery where " soap lyes " are to 
be evaporated, as it keeps concentrating in the glycerine liquors 
during the boiling, and requires the frequent dropping of these 
liquors during the process of making crude glycerine to elim- 
inate this salt. Besides, the steam-chests of the evaporators 
become coated with salt during the boiling and insulates the 
heat. 

The original " soap lye " solution contains about 3 per cent 
of glycerol, while the " Twitchell " liquors carry about 15 per 
cent glycerol, thus saving a great deal of evaporation. 

c. With the fatty acid at hand, it is possible to make soap 
directly in the crutcher by the mixing of the fatty acid, alkali, 
saponified rosin and filling material. 

The fact that the fatty acids produced are somewhat darker 
than the original stock has been the chief objection to this 
method of treating fats and oils. At present there are im- 
provements being made in this process which claim to over- 
come this defect. If successful it will lead to a more general 
use among the soap-makers, as at present it is used chiefly by 
the candle-makers for producing stearic and oleic acids. 

SOAP OR WASHING POWDERS. These powders are mixtures 
of soda ash (dry Na2COs), soap (mixed in liquid condition), 
and water, the only difference in the many kinds on the market 
being in the amount of these ingredients present and the kind 
of soap used. According to the amount of water present, there 
are two general classes: those containing 10 to 20 per cent of 



332 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



water being the old-style and those having 35 to 40 per cent of 
water, or the new-style, called usually " fluffy powders." 

SCOURING POWDER. This powder is made by mixing 
varying amounts of soap powder, silex (grit), talc, and some- 
times a small amount of sal ammoniac. 

SCOURING SOAPS. These soaps are generally made on a 
cocoanut-oil base. The soap after saponification is drawn to 
a crutcher, silex (grit) is mixed with it and the mass dropped 
into an asbestos-jacketed kettle or tank and run into slate molds 
to harden, each mold being the size and shape of the finished 
soap. 

BOILED TOILET SOAPS. The method of boiling for toilet 
soap is the same as for laundry soap, except that a different 
variety and grade of fat is employed. The 
raw materials consist mostly of vegetable 
oils to which a small amount of tallow is 
added. No rosin, however, is added, as the 
vegetable oils possess sufficient lathering 
quality. On completion of the boiling 
operation the soap is run to a continuous 
drying chamber, where it falls on an end- 
less belt and is slowly conveyed through 
the drying apparatus, coming out in the 
proper condition for the subsequent opera- 
tions. An older method, and one which is 
still used in many factories, is to crutch, 
frame, slab, cut, and then " chip." The 
" chipper " (Fig. 106) consists of an en- 
closed disk provided with knives which re- 
volve at a high rate of speed, and against 
which the bars of soap are pressed. The 
chips thus obtained are dried until brittle 
and are then ready for the subsequent operations. 

AMALGAMATOR. This machine (Fig. 107) is used for mixing 
the color and perfume with the chips before milling. With the 
use of an amalgamator a more uniform soap is obtained and at 
least one milling saved. In the old method of adding color and 
perfume to a soap, the chips were mixed in a box with color 
and perfume by a shovel. A uniform distribution of color and 
perfume was almost impossible by this method, and required 
five or six trips through the mill to produce the desired uni- 
formity. An even mixture may be obtained in an amalgamator 




Fig. 106. 



SOAP, SOAP POWDER AND GLYCERINE 



333 



in about fifteen minutes, and 
twice milling this product is 
sufficient. 

In the majority of toilet 
soap factories, in making up 
their stock, they go in the 
order of their color, starting 
with white and then making 
the next darker shade, like 
yellow, then green, pink, etc., 
until they finish with the 
darkest soap, usually tar soap. 
In this way the machine will 
only need one cleaning. 

MILLING. Whether the 
soap has been dried by the 
modern method or by the 
slower method of chipping, it 
is placed in a mixing ma- 
chine, where the necessary perfume, color, or other ingredients 
are added. It is then fed to the " mills." These mills con- 
sist of two or more rollers (Fig. 108) between which the soap 




Fig. 107. 





Fig. 108. 



334 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



passes, thereby causing the added material to become well in-. 
corporated. The usual practice is to pass the soap between the 
roller six times or until the corrugated flakes have a perfectly 
uniform and smooth appearance. 

PLODDING. The milled soap is placed in the hopper of a 
machine known as the " plodder " (Fig. 109), where it is subjected 
to great pressure by means of a compression screw. In the 
nozzle of the plodder is a "forming plate" having an opening 

the size of the cake de- 
sired. The flaky condition 
of the soap as it comes 
from the mills is converted 
into a continuous bar, 
which may be cut to any 
length and stamped or 
pressed as desired. 

Milled soaps allow of 
the use of delicate per- 
fumes or other materials 
which would be destroyed 
if incorporated with the 
hot soap in the crutcher. 
The price of a soap de- 
pends largely upon the kind 
of perfume which is used to scent it, as out of the same kettle of 
soap may be prepared an article selling for ten cents or one 
dollar. Some toilet soaps are slightly superfatted, so as to over- 
come the harsh effect of an alkaline condition. 

SOFT SOAPS. Soft soaps are usually prepared by employ- 
ing potash as the alkali and an oil high in oleic acid as the fatty 
material. Saponified red oil, linseed oil, rosin, and cotton seed 
oil are among the chief oils used for the purpose. 

LIQUID SOAPS. These soaps are made in the same manner 
as soft soaps and are given their liquid property by addition of 
glycerine or alcohol. Liquid soaps are made from selected stock 
and the lye well settled before using. Cocoanut oil is largely used 
for this variety of soap. 

HALF-BOILED SOAPS. As the name implies, soap made 
by this process is not boiled. The operation is always conducted 
in a crutcher, the temperature of the stock being raised to about 
160° F., and the lye added. The mixture of lye and fat is 
crutched for about five minutes and allowed to stand undisturbed 




Fig. 109. 



SOAP, SOAP POWDER AND GLYCERINE 335 

for two hours. It is then crutched again until smooth, tested 
for excess of either fat or alkali, run into frames, allowed to set 
and harden as stated under boiled soaps. Half-boiled soaps con- 
tain all of the glycerine originally combined in the oil, and for this 
reason give a very satisfactory soap for toilet purposes. As there 
is no recovery of the glycerine it cannot be worked economically 
for laundry soaps. After settling and cooling, it may be chipped, 
milled, plodded, and pressed in the same manner as boiled soaps. 

COLD-PROCESS SOAPS. Soap made by this process differs 
from half-boiled soaps in that the oils are only heated to their 
melting-point and the lye added. The operation is conducted 
in a crutcher and the mixture stirred until smooth, when it is 
dumped into the frames. 

Floating Soaps. The soaps which float on water are 
prepared in the same manner as other soaps, and the specific 
gravny lowered by crutching at a high rate of speed, so as to pump 
the soap full of minute air bubbles. The same result is obtained 
by reversing the direction of the paddle several times during the 
crutching. Floating soap is never milled, but on cooling in the 
frames it is cut into cakes and pressed. 

MOTTLED SOAPS. The old-style mottled soaps were made 
by boiling in a kettle over the open fire and run into frames to 
cool. During the long process of heating, certain decompositions 
took place, so that when the soap cooled very slowly the excess 
of lye and impurities segregated to those portions which were the 
last to solidify. At present the same effect is produced by 
crutching with ferrous sulphate, ultramarine, lamp-black, or other 
pigment just before the soap is run into the frame. Castile or 
Marseilles soap sometimes have a green mottle, which changes 
to red on exposure. This is due to the presence of ferrous sul- 
phate, which has been acted upon by the lye to produce ferrous 
hydroxide; which in its turn is changed to ferric hydroxide by 
exposure to the air. 

CASTILE SOAP. This soap is supposed to be made from 
olive oil and soda lye only, but as a pure olive oil soap becomes 
excessively hard and brittle on standing, other oils are usually 
added. The oils used for this purpose vary, cocoanut, linseed, 
cotton seed, and corn oil being usually employed. The color of 
the oil influences the color of the finished product, so that we 
have both white and green Castile soap, due to using either a light 
or colored oil. Practically all Castile soap is either made by the 
cold or the half-boiled process. 



336 ELEMENTS OF INDUSTRIAL CHEMISTRY 

TRANSPARENT SOAPS. These soaps are usually made by 
dissolving a good soda soap in alcohol, decanting away from any 
insoluble matter and distilling off the excess of alcohol. This 
leaves the soap in the form of a transparent jelly, which is dried 
out in molds having the form of the cake desired. Transparent 
soaps are also made by the cold or half-boiled process, by adding 
more glycerine together with a small amount of alcohol and any 
perfume or coloring matter which may be desired. A cheaper 
grade is made by adding a solution of cane sugar. 

SHAVING SOAPS. These are usually soda and potash com- 
bination soaps, made from high-grade stock. They may be made 
on a cocoanut-oil base with the addition of stearic acid to give 
body, and a gum to keep the lather from drying. Many shaving 
soaps contain glycerine or sugar. 

SHAVING CREAMS. These are potash soaps usually made on 
a cocoanut-oil base to which is added a certain percentage of 
stearic acid. 

TOILET POWDERS. Most toilet powders are composed 
largely of talc, to which varying amounts of calcium or other 
stearates have been added. Some powders also contain anti- 
septic substances such as boric acid. 

SOAP POWDERS FOR TOILET USE. These powders are 
prepared by completely drying a good grade of toilet soap and 
subsequently pulverizing it. They must be as near neutral as 
possible to avoid any irritation when used on tender skin. 

METALIC SOAPS. By adding soluble salts of the heavy 
metals to a neutral soap solution a precipitate of metallic soap is 
obtained. Some of these metallic soaps have very extensive 
application in the industries and in pharmacy. The lead soap 
produced by adding lead acetate to a linseed-oil soap is used as 
a drier in mixed paints. By boiling olive oil with lead oxide 
" lead plaster " is obtained. 

Sources of Glycerine. The world's output of crude 
glycerine is estimated at about 85,000 tons. It is exclusively 
a by-product industry of the soap and candle trades and the 
output depends not so much on the demand for glycerine as on 
the world's requirements of soap and candles. The cause of this 
condition is the relatively small percentage of glycerine obtainable 
from the fats, the theoretical amount ranging from 10.5 per cent 
with tallow to 13.5 per cent with cocoanut oil. In practice this 
is cut down by the free fatty acids always present, each 10 per 
cent of free fatty acids reducing the glycerine by about 10 per 



SOAP, SOAP POWDER AND GLYCERINE 337 

cent. With the increasing use of high grade fats for butter sub- 
stitutes and the conversion of fatty oils to hard edible fats by the 
use of hydrogen and catalytic agents the soap- and candle-maker 
are compelled to resort to fats and oils of poorer quality than 
formerly. These fats are high in free acids and low in glycerine, 
so that the tendency seems to lie in the direction of lower yields 
in the future than in the past. 

Glycerine is a by-product of the alcoholic fermentation of 
sugar, the amount produced being variously stated as 3-8 per 
cent of the alcohol formed. At any rate, enormous quantities 
must go to waste in the residues from alcohol stills, as to date 
no commercial process has been developed for the recovery of 
this glycerine. 

Glycerine has been subject to wide fluctuations in price, the 
dynamite grade selling for 10 cents a pound in 1908 and 60 cents 
in 1916. The United States does not produce sufficient glycerine 
to meet its own requirements and there are from 30,000,000 to 
40.000 000 lbs. of foreign crude imported annually. 

SAPONIFICATION. Only those industries requiring fatty 
acids in large amount can afford to produce crude glycerine. The 
candle-maker wants primarily the white, hard stearic acid. The 
soap-maker is after the combination of the fatty acids with soda 
in the form of soap and utilizes all of the higher fatty acids 
present. To separate the fatty acids from a fat it is necessary 
to break it up into its constituents. This process is called saponi- 
fication and is brought about by the interaction of water and fat, 
fatty acid being split off and glycerine being produced. The 
decomposition with water alone is slow and requires very high 
temperatures. It is greatly facilitated by the addition of a 
catalytic agent, which may be of an acid or alkaline character. 
In the soap industry caustic soda is used, the soap formed emulsi- 
fying the fat and exposing a large surface of fat to the action of 
water. In the candle industry a small percentage of lime or 
magnesia is used, and the reaction hastened by a high temperature 
obtained by the use of autoclaves under a steam pressure of 250 
pounds. In the Twitchell process, used by both the soap and 
candle industries, the catalyzer is a sulfo-fatty acid, the hydrogen 
ion assisting the reaction and the sulfo-fatty acid acting as an 
emulsifier. 

SOAP-LYE CRUDE GLYCERINE. This forms the principal 
source of supply. After the saponification of the fat by caustic 
soda the soap is thrown out of solution by the addition of salt. 



338 ELEMENTS OF INDUSTEIAL CHEMISTRY 

The mother liquor or spent lye contains 4-5 per cent glycerine. 
All the salt and the bulk of the impurities present in the fat is 
purified by the addition of a crude persulphate of iron, obtained 
by the action of oil of vitriol on pyrites cinder or iron ore, or by 
the use of aluminium sulphate. A precipitate of the hydrate is 
thrown down, carrying with it albuminoids and metallic soaps 
of the higher fatty acids. This is removed by a filter press. The 
purification is only a partial one, and in case low grade stock 
has been used large amounts of impurities remain in the dilute 
glycerine. 

The next step is evaporation, formerly considered a process 
of great difficulty when fire-heated kettles were used, as the salt 
caked on the sides of the vessel. The modern method is to con- 
centrate in a vacuum evaporator. At a vacuum of 27 to 28 
inches the boiling point is reduced to such a degree that the salt 
separating does not adhere to the heating tubes, but drops into 
a chamber placed below. Exhaust steam may be used during 
the greater part of the evaporation, live steam being used to finish 
off. The salt is raked out on a vacuum-filter and is washed 
practically free from glycerine and returned to the soap-kettle. 

Crude glycerine when cold has a specific gravity of 1.30 or 33.5° 
Be. It is a saturated solution of mineral salts in glycerine and 
water. The salts consist largely of sodium chloride with some 
sulphate and the sodium salts of the lower fatty acids. It is 
slightly alkaline with soda. The glycerine is usually about 80 
per cent. It may run down to 60 per cent in bad crudes and up 
to 87 per cent in highly concentrated crudes of the best quality. 
The organic matter not glycerine will average 2-3 per cent in good 
glycerines. The ash will run from 8-10 per cent in good crudes; 
15 per cent and more in bad crudes and crudes carrying solid 
salt. 

Soap-lye crude may be easily recognized by its high salt con- 
tents when tested by silver nitrate, giving a heavy curdy precipi- 
tate. With basic lead acetate a heavy precipitate of oxy chlor- 
ide of lead is obtained. The specific gravity is high. 

Saponification Crude Glycerine. This is the by- 
product of the candle industry and the glycerine obtained when 
fats are split up by the Twitchell process, the fatty acids being 
used in the candle or soap trades. It is free from sodium chloride 
and practically free from mineral matter in the purer grades. 
The thin liquor from the autoclaves or Twitchell saponifying 
tanks after settling to separate the free fatty acids is treated 



SOAP, SOAP POWDER AND GLYCERINE 339 

with a little lime or aluminium sulphate and filter-pressed. It is 
then evaporated to a specific gravity of 1.24 at 60° F. or 28° Be. 
The glycerine standard for saponification crudes is 88 per cent. In 
poor grades it will sometimes run down to 82 per cent and less and 
occasionally is as high as 90 per cent in high-grade crudes. The 
ash standard is 0.5 per cent and the organic residue 1 per cent, 
although these figures are sometimes greatly exceeded. As a 
rule Twitchell saponifications are inferior to the autoclave crudes, 
not because the process is at fault, but because the Twitchell 
method makes available the use of low-grade fats and greases, 
which cannot be profitably treated in the autoclave. 

A saponification crude is distinguished from a soap-lye crude 
by the absence of salt, as shown by the silver nitrate test, by its 
low specific gravity and small precipitate with basic lead acetate. 
The latter may be heavy in bad crudes, but is of a flocculent char- 
acter and easily distinguishable from the precipitate of lead oxy- 
chloride. Basic lead acetate affords a good method of finding 
the quality of saponification crudes, as a high-grade product gives 
only a slight precipitate. 

Crude glycerines produced by the fermentation process are 
but rarely met with. 

PURIFICATION. Crude glycerine contains mineral impurities, 
such as salt, sodium sulphate, carbonate, hydrate, acetate, buty- 
rate, caproate, etc., together with iron, lime, arsenic and other 
metals. As volatile impurities may be enumerated fatty acids 
split off from the sodium salts, acrolein produced during distilla- 
tion, ammonia and amines, sulphur compounds and trimethylene 
glycol. The last-named is contained in low-grade crudes derived 
from products subject to fermentation. There are also non- 
volatile organic substances present, such as albuminoids, resinous 
bodies and polyglycerols. 

The only method used for the separation of glycerine from 
these substances is distillation combined with fractional con- 
densation. By careful distillation the non-volatile substances 
are left behind in the still, and by careful control of the tempera- 
tures of the condensers the glycerine is condensed before the more 
volatile impurities. 



CHAPTER XVII 

ESSENTIAL OILS 

CRUDE DISTILLATION. Many of the essential oils are dis- 
tilled by unskilled natives in the various countries, and the layer 
of water is usually heated by direct fire placed under the still. 
It is now well known that this both decreases the yield and pro- 
duces an oil inferior in quality, as it subjects the material to the 
saponifying or hydrolizing influence of hot water and some 
small particles of the substance being distilled are sure to adhere 
to the bottom of the still, where they scorch, and contaminate the 
distillate with a burnt odor. 

Modern Distillation. In modern factories steam is 

generated in a boiler and passed into the still at various degrees 
of pressure. Usually the still is also heated either by means of 
a steam jacket or by a closed steam pipe placed inside the still, 
so as to prevent much condensation of the steam in the still. 
The degree of fineness of the charging material, the pressure, 
and therefore the temperature of the steam, the speed of its 
flow and numerous other working points must be adapted in 
each case to the apparatus in use, as well as to the substance that 
is being distilled and the product that may be expected. 

The odor and taste of all natural products are due in almost 
every case to a combination of a number of chemical bodies and 
it is only when these chemical individuals are assembled in the 
right proportion and combination, that the odor of the flower or 
material will be duplicated. Many of these chemical bodies are 
extremely sensitive to heat, which either destroys them or changes 
the odor completely, others are esters which are hydrolized by the 
action of steam and heat and many plants contain bodies which 
upon heating act to a greater or less extent on the other constit- 
uents. Consequently, steam distillation has its limitations and 
other processes must be utilized to extract the active principles 
desired. 

EXPRESSED OILS. That squeezing the rind of some fruits 
left a fragrant oil on the hands must have been early observed. 

340 



ESSENTIAL OILS 341 

It is still the method which gives the finest oils of the citrus 
family and is the present commercial method of obtaining the 
oils of lemon, orange and bergamot. As cheap labor is available 
in Sicily, where these oils are made in quantities, and the pulp 
of the fruit is worked up for citric acid, the price remains quite 
low, although the method is slow and tedious. The peel is man- 
ipulated, crushing the oil cells and the oil is absorbed by a sponge, 
which is then squeezed and the oil filtered for the market. 
Machines have at times been tried to take the place of hand labor, 
but none of them have been found commercially satisfactory, 
excepting to a limited extent for the regularly shaped bergamot. 

MACERATING PROCESS. The process of macerating con- 
sists in placing the flowers in warm oil or fat, a method by which 
the modern flower pomades are produced in southern France. 
After the oil or fat has absorbed the odor of the flowers, it is 
strained off and a fresh lot of flowers added. This process is 
repeated a number of times, according to the strength of pomade 
desired. 

ENFLEURAGE PROCESS. It was found, however, that even 
the slight heat necessary in the macerating process is sufficient 
to destroy some of the more sensitive constituents of some flower 
odors, and so the cold enfleurage process resulted. Here a layer 
of fat is placed on a plate of glass, fresh flowers are sprinkled 
on it and after the fat has absorbed the odor, they are replaced 
by more flowers, and this process is repeated until the fat is 
saturated. This process is especially adapted to flowers like 
the jasmine blossom, which is known to produce perfume for 
some time after it has been picked and a much better yield 
results than when the flower is immersed in hot fat, which im- 
mediately stops the production of more flower oil by the blossom. 

FLOWER POMADES. This flower pomade, obtained either 
by maceration or by the enfleurage process, is then washed with 
alcohol, which extracts from the pomade the odorous substances 
absorbed from the flowers. 

VOLATILE SOLVENTS. Objection to the above processes 
has led to the more modern process of treatment by volatile 
solvents. Petroleum ether, carbon tetrachloride, chloroform, 
and other volatile bodies have been used for this purpose. These 
solvents, in passing through a layer of flowers or materials, dis- 
solve the odorous constituents, together with the plant resins, 
coloring matter, waxes and other substances present, which are 
soluble in the solvent utilized. By then distilling off the sol- 



342 ELEMENTS OF INDUSTRIAL CHEMISTRY 

vent at a low temperature, usually in a partial vacuum, the 
odorous bodies, with the impurities mentioned, remain in the 
residue. As the yield from different flowers varies greatly, 
various quantities of wax, paraffine or some liquid odorless ester 
are usually added to reduce the cost and in order to market 
the different odors at the same price. 

Flower Concretes and " Absolutes." By this method 
the so-called " flower concretes " are made in southern France. 
This process has recently been improved again by eliminating 
from this concrete the alcohol insoluble portion. The concrete 
is treated with alcohol, thus extracting only the alcohol-soluble 
constituents and the alcohol distilled off, which gives a final 
product, marketed under various trade names, but usually 
called " absolute flower concrete " or " absolute flower essence." 
In another process, the waxes naturally present are precipitated, 
separated, and the solvent then evaporated in the usual manner. 
Other of these essences are obtained by washing the pomades 
and distilling off the alcohol. 

CONSTITUTION OF PERFUME AND FLAVORING MATERIALS. 
The complex nature of these has only been properly studied in 
recent years. 

As organic chemistry progressed and methods were found 
to identify and isolate from the natural materials various con- 
stituents present in them, it was found that almost without excep- 
tion every odorous material in nature is a compound. Quite 
frequently materials contain chemical substances or individual 
chemical bodies belonging to entirely different series and in no 
way related to each other. Some of these substances are ex- 
tremely sensitive to heat and chemical reagents, and therefore 
their isolation and identification present the greatest difficulties, 
but it is just this combination of different chemical individuals 
to which the fine odor of almost all flowers, plants, and other 
materials is due. As a rule, all of the definite chemical con- 
stituents, when used alone, give harsh odors. The delightful 
flowery aroma is only developed when they are present in proper 
combination, as they exist in nature, or as the skill of the chemist 
may combine them. This has led to commercial synthesis 
of the finer flower products. 

SYNTHESIS. The collaboration of thousands of chemists 
throughout the world, for some years past, has made a new 
industry possible, the industry of synthetic perfume and flavoring 
materials, which has come to the assistance of the manufacturer, 



ESSENTIAL OILS 343 

by producing the same substances at a saying in cost, and by 
overcoming the frequent price fluctuations of the natural mate- 
rials, war conditions excepted. Many of the substances which 
naturally exist in the plants or materials may be manufactured 
chemically from other sources. Let us select one example, the 
jasmine flower, w T hich is so invaluable to the perfumer. If w T e 
submit the so-called " absolute jasmine-flower essence or con- 
crete " to a further process of purification, to eliminate the 
inodorous constituents present in it, we finally obtain a jasmine 
essence, which contains from 60 to 65 per cent of benzyl acetate. 
The absolute product containing this percentage, as made from 
the blossom, represents an actual expense of about $180 
to $260 per pound, according to season. But we can obtain 
benzyl acetate chemically if we take toluene (methyl benzene), 
and treat it > with chlorine, we obtain benzyl chloride. If we now 
exchange the chlorine for the acetyl group, we get benzyl acetate, 
which, when highly purified, is identical with the product as it 
exists in the flower, and is marketed absolutely pure at about one 
hundredth the cost. This not only represents an enormous sav- 
ing in the industry, but makes it possible to use raw materials 
frequently for various purposes, where the natural product was not 
heretofore available, owing to its high cost. But while this syn- 
thetic benzyl acetate is absolutely the same definite chemical body 
as found in the flower oil, it is not jasmine. What we know 
as jasmine is nature's combination of many different constit- 
uents and we do not get what we call a jasmine odor until 
we produce each of these constituents and assemble them in 
the right proportion. By suitably changing the proportion of 
these constituents, we can obtain new odor effects, different 
shadings of the same flower odor. Flower oils are usually 
exceedingly complex. Often more than one hundred different 
chemical bodies must be produced and assembled to duplicate 
an odor known as " a simple flower odor " because each of these 
bodies is present in the plant and we cannot get the same odor 
effects unless we unite the same constituent bodies. 

NEW PERFUME MATERIALS. A great many chemical sub- 
stances have been found which have most delightful odors and 
flavors, and which, to our best knowledge at the present time, 
do not exist in nature as siich — at least, they have not been 
isolated from the natural materials. Many such substances are 
now commercially manufactured and have enriched the industry 
with a variety of new raw materials, which enables the manu- 



344 ELEMENTS OF INDUSTRIAL CHEMISTRY 

facturer to produce entirely new effects. Many years ago, when 
the industry was in its infancy and purification processes had 
not developed to the present state of perfection, the synthetic 
materials were merely used for the purpose of diluting and 
cheapening the more expensive natural products, but this has 
wholly changed during the last few years. The synthetic materials 
of to-day are successfully utilized in goods of the highest grade, 
and many odor and flavor effects would be impossible without 
them. 

Chemical Constitution. Among the many chemical 

bodies which contribute their share to the odor or flavor of 
materials valued in the industry, we find representatives of both 
the aliphatic or fatty series and the aromatic or benzene series. 
The great majority consists of merely three elements, carbon, 
hydrogen, and oxygen. A smaller number of compounds, some 
of which are important, contain nitrogen — for instance, different 
varieties of artificial musk and amido bodies, derivatives of 
the benzoic acid series, like methyl anthranilate, one of the most 
valuable constituents of orange flower and many other 
flower oils, and the methyl ester of methyl anthranilic acid or 
dimethyl anthranilate, which, while present usually only in 
traces, contribute greatly to the flowery sweetness of many 
of nature's most valued blossoms. 

FIXATIVES. Some products which have but little odor are of 
value to the industry, because they are substances the perfumer 
calls "fixatives." In the plant, the perfume is produced con- 
tinuously in mere traces and is given off in infinitesimal quantities 
to the surrounding atmosphere. When we, however, isolate 
these bodies to which the odor is due, and have them in concen- 
trated form, their odor as given off is too intense and when we 
take a small amount of this concentrated material and allow it 
to evaporate, the odor will not last as long, because it will evapo- 
rate more quickly than in the plant and, furthermore, the odor 
being so concentrated and intense, will not be as sweet or as 
flowery. If we, however, use with the material various sub- 
stances known as fixative's, the odor is made less volatile. The 
perfume is only given off in small quantities at a time and we 
therefore duplicate the conditions existing in nature. In former 
times, ambergris, musk, and some of the resins were extensively 
used as fixatives, but most of these substances either had such 
a powerful odor, color, or sticky qualities (resins), that they could 
not always be used in sufficient proportion entirely to satisfy. 



ESSENTIAL OILS 345 

Modern organic chemistry has given us a number of sub- 
stances, which, while practically of no odor value themselves, 
are very valuable in combination, because they not only serve as 
fixatives — that is, make odors with which they are mixed less 
volatile, but in many instances have the tendency to sweeten the 
odor. Among representative instances of this class we may men- 
tion methyl anisate, benzyl benzoate, benzyl cinnamate, and 
benzyl-iso-eugenol, which have but little odor. Then we have a 
group of very useful materials which combine a delightful odor 
with valuable fixative properties, as the many varieties of artifi- 
cial musk, phenylethyl phenylacetate, which has a charming 
rose-like fragrance, the various moss odors as Mousse de Chene, 
Mousse de Perse, Mousse d'Orient, and many other products 
valuable as fixatives wherever their odor harmonizes with the 
other constituents utilized. 

MUSK. Musk is perhaps one of the oldest perfume materials 
in existence and consists of the dried secretion of the preputial 
follicles of the male musk deer. This animal has been hunted 
so excessively that it has become practically extinct and it is 
now found only in the portion of Asia where the Himalaya Moun- 
tains rise to elevations of 8000 to 12,000 ft. Occasionally the 
animal may wander into lower altitudes, but the greater part of 
the annual production comes from the Himalaya region. In 
Siberia we find musk deer, allied in family, but the musk secreted 
by them is not valued as highly in commerce and does not have 
as powerful an odor. The musk pods are purchased by native 
dealers, carried by caravans to the seashore and marketed from 
Chinese seaports. Commercially the product is known as either 
Nepaul or Tonquin musk and is now valued at from $20 to $25 
an ounce. It is becoming scarcer each year, and the time is not 
far distant when the musk deer will be extinct, because each 
musk pod means that a male musk deer has been killed. Of 
course adulterations are plentiful. The Chinese have excelled 
in this, and have for many years past sold so-called artificial musk, 
w r hich is a mixture of dried blood and various other substances, 
hard to identify, with just a trace of natural musk, marketed at 
prices ranging from $1 per ounce, upwards. The chemical 
substance to which musk ov/es its odor has never been definitely 
identified. Some research work of recent years seems to point 
to a ketone, which gives a powerful musk odor, but no chemical 
work of note has been done on the subject, owing to the high 
expense involved, and the exact chemical formula of the product 



346 ELEMENTS OF INDUSTRIAL CHEMISTRY 

is still in doubt. Musk also contains a number of impurities, 
which rather detract from the true musk odor, but are always 
present in the natural article. 

SYNTHETIC MUSK. If we now turn to synthetic musk, we find 
that here we encounter a product differing entirely in chemical 
composition, imparting a musk odor, and of which many chemical 
derivatives have been made. The original musk marketed was 
a trinitro derivative of toluene, and later a trinitro derivative 
of xylene. Xylene, may be condensed with iso-butyl chloride, by 
means of aluminium chloride — that is by the well-known Friedel 
and Kraft reaction, to form iso-butyl -xylene. After careful puri- 
fication, this substance is nitrated in the usual way, by employing 
a mixture of sulphuric and nitric acids, and the final product is 
thoroughly purified by repeated crystallization. This gives us the 
artificial musk of commerce, trinitro-iso-butyl-xylene, C12H15O6N3, 
consisting of small, yellowish, needle-shaped crystals, having 
a peculiar musk odor. This artificial musk is utilized in many 
perfume compositions all over the world to-day, and while it 
has not the identical odor of natural musk it has replaced it in 
numerous instances in the soap and perfume industry. The 
success of these products encouraged scientific research, and as 
a result a number of other musk compounds have been made 
which have a stronger and sweeter odor. Among these we may 
mention musk ketone, also a nitro product, in which, however, 
the CO or ketone group is present. Ambrette musk and similar 
derivatives, made by other complicated 'chemical processes, have 
a more intense odor than any other artificial musk known and 
some of them have the advantage of being more soluble. 

CIVET. Civet is the secretion of the civet cat of Abyssinia, 
where the cat is kept for the purpose of producing a regular sup- 
ply. It is a substance somewhat similar to musk, but contains 
derivatives of indol, principally one of the methyl-indols, as 
active constituents. As brought into commerce, it is largely 
adulterated with fats and fatty substances, hairs, clay, etc. 
The substances present in natural civet, which give it fixative 
value, have been identified chemically and are produced syn- 
thetically. Civet materials are now available, both in liquid 
and crystal form, as well as the active principle to which the 
odor of civet is mainly due, namely, one of the methyl indols, 
C9H9N. 

AMBERGRIS. Ambergris is another product belonging to 
this series, and is supposed to be a decomposition product present 



ESSENTIAL OILS 347 

in the intestines of unhealthy whales. Its use has largely de- 
creased in recent times, as synthetic substitutes have become 
available at a small fraction of the cost of the natural article, 
the supply of which is very irregular and uncertain. 

CASTOREUM. Castoreum is a product from the beaver, 
which has a similar odor to musk. It is now but seldom used. 

GUM BENZOIN. Of the fragrant gum resins known to the 
ancients, but few have survived. Gum benzoin is used in medicine 
to-day and forms a constituent of many toilet preparations. 
Sumatra gum benzoin has a dark brown color and is only fit for 
medicinal use — it should never be employed for perfumery 
purposes. The gum coming from Siam or Rangoon is the only 
variety suited for use in perfumery. It is practically colorless. 
Gum benzoin is chemically of interest, because from it benzoic 
acid was first isolated and it has given its name to the chemical 
benzene or benzol CeHo. Then we have gum olibanum or frank- 
incense, and myrrh — Arabian gums of sentimental, rather than 
practical, importance, although used in the manufacture of incense. 

STYRAX. Styrax from Asia Minor is another gum of decreas- 
ing importance, in which, however, important chemical bodies 
have been found — among them styrol previously mentioned, as 
well as cinnamic acid and cinnamic alcohol, both of which are of 
importance. 

BALSAM PERU. Balsam or gum Peru is improperly named, 
because all of it comes from the Republic of Salvador in Central 
America. This balsam is obtained by crude methods over a 
direct fire and has a rather smoky odor. It is too sticky to find 
application in perfumery and is employed in medicine. There 
is, however, the so-called oil of balsam Peru, which is separated 
from the balsam by chemical means, eliminating the resins, which 
has a very nice odor, although contaminated by the burned 
smoky smell, due to the phenolic constituents, which result from 
heating the balsam over direct fire. The product has been ana- 
lyzed repeatedly and synthetic reproductions are on the market, 
which are superior in odor to the natural. 

GUM LABDANUM. Then we have the old gum labdanum 
mentioned in some of the ancient works on perfumery, the black 
color and stickiness of which prevented its extended use. Chem- 
istry has enabled us to isolate from the gum the portion to which 
the real odor is due, which is now largely employed in the most 
modern creations and imparts all of the odor value and fixative 
value of the gum, without the color and stickiness. Labdanol 



348 ELEMENTS OF INDUSTRIAL CHEMISTRY 

is indispensable in many high-grade bouquets, as it imparts a 
delicate softness to the odor and acts as a most excellent fixative 
as well. 

FLOWER PERFUME MATERIALS. These include our finest 
odors, perfumery products isolated from the flowers by means of 
either the enfleurage or maceration process, or synthetic repro- 
ductions of these materials. All of these products are exceedingly 
complex in character and owe their fine perfume to the proper 
blending of many distinct chemical bodies, produced in such 
lavish profusion in nature's laboratory. These materials form 
the most important group available for duplicating the delight- 
ful blossom fragrance, and include all blossom oils, concretes, 
" absolutes," pomades, and washings from same, and all the 
fine synthetic flower perfume oils. Many of the different flower 
odors contain a number of the same constituents, but in widely 
differing proportions and influenced by the odor of other bodies 
present. 

GERANIOL AND ClTRONELLOL. In the rose we find the ter- 
pene alcohols, geraniol and citronellol, present in large pro- 
portion. These are closely allied chemically. Geraniol has the 
formula CioHigO, and citronellol C10H20O. Citronellol has 
not been found alone, but is usually accompanied by geraniol. 
As the commercial separation of these two alcohols is only possible 
by destroying the greater part of the geraniol present, the use of 
citronellol alone, which does not exist by itself in the flower 
anyway, is not advantageous. Under the name of rodinol, or 
rhodinol, a mixture of geraniol, citronellol, and isomeric alcohols 
is marketed, containing the proportion of allied alcohols present 
in roses. It has a very sweet rose-like odor when perfectly pure 
and is used in quantities. Citronellol is also produced artificially 
from the allied aldehyde, but this product lacks that soft sweetness 
which is the characteristic of rodinol. The esters' of geraniol 
and rodinol are likewise of importance, the acetates, formates, 
and propionates having a very sweet flowery odor. 

Rose Oil and Rose-flower Products. Turkish otto is 

one of the highly prized perfumery products used throughout 
the world. Turkey does not produce even a small proportion of 
the crop; almost all of it comes from Bulgaria; of late Asia 
Minor and Persia also produce a limited quantity. As previously 
mentioned the oil consists largely of geraniol, citronellol, and 
allied alcohols with a small proportion of their esters, as well as 
about 20 per cent of an entirely odorless, waxy hydrocarbon 



ESSENTIAL OILS 349 

belonging to the parafnne series. Much of the oil is impure. 
The official figures show the importation into Bulgaria of quan- 
tities of products that may be used as adulterants for oil of rose 
and the export of a great deal more rose oil than the statistics 
show has been produced. The rose-flower products have a much 
finer perfume than the distilled oil, or otto, and are available in 
many modifications. Rosa centifolia is used for manufacturing 
rose concretes, pomades, and absolutes. The blossom oil con- 
tains up to 80 per cent of alcohols, principally phenylethyl 
alcohol, which is almost entirely absent in the steam-distilled 
otto, as it passes into the rose water. Oils imparting the odor of 
the tea rose, red rose, moss rose, white rose, and other varieties, 
are available. All of these members of the rose family contain 
other constituents in varying proportions, hence in order to 
duplicate their odor we must utilize many different chemical 
bodies. 

PATCHOULY OIL. The patchouly plant is principally ob- 
tained from the Straits Settlements and Java, where it has 
been cultivated so long that it has almost wholly lost the 
habit of flowering. The oil, which is distilled from the leaves, 
increases in value on aging. By chemical methods the oil 
may be purified and the undesirable constituents which have 
a moldy, disagreeable odor, removed. The resulting products 
can be used without hesitation in the finest perfume combinations, 
but only in small proportion. If employed in too large a quantity 
the effect will not be agreeable. 

Orange-flower and Neroli Products. One of the oils 

which owes much of its odor value to esters of linalool is the oil 
of neroli, distilled from orange blossoms. Neroli oil, being 
made by steam distillation, does not represent the entire odor 
value of the flowers, but having become a commercial product 
many } T ears ago, is esteemed by manufacturers of cologne, and 
is also used as a flavor to a limited extent. " Orange-flower 
water " is obtained as a by-product, and contains the saponified 
portion of some of the constituents present in the blossom. It 
may be had at a fair price, considering the fact that the pur- 
chaser must pay for the transportation of distilled water from 
Europe. A number of different varieties of neroli are known, 
neroli petale being the finest grade, neroli bigarade coming next 
in quality, after which there are various inferior grades, ending 
with the so-called oil of petitgrain. This is imported from South 
America, where it is distilled by crude native methods from twigs, 



350 ELEMENTS OF INDUSTEIAL CHEMISTEY 

leaves, unripe fruit, as well as flowers of the wild orange trees, 
which have spread from those planted there when Spanish friars 
controlled that quarter of the world. Oil of petitgrain is fre- 
quently used to dilute the more valuable neroli oils. Orange- 
flower products made by enfleurage or synthesis differ greatly 
in composition from distilled neroli oils as they represent all the 
blossom constituents. The flower oils therefore have a much 
sweeter and finer perfume than neroli oils and are indispensable 
in fine perfumery. 

JASMINE-FLOWER PRODUCTS. The jasmine odor is one of 
the most useful perfumery raw materials, indispensable in many 
bouquets, as it imparts great freshness and delightful odor effects. 
Jasmine-blossom oil contains principally the benzyl esters of 
acetic, formic, and propionic acids, linalool and its esters, methyl 
anthranilate, benzyl alcohol, geraniol, paracresol, a ketone jasmon 
and traces of a number of other constituents. Cape jasmine 
or gardenia oil belongs to the same odor class, but is less fleeting 
and has a more intense sweetness. 

YLANG YLANG OIL. Ylang ylang oil has long been one of 
the most valuable products of the Philippines. The distilled 
oil is a very complex body which differs somewhat from year to 
year and according to the method of production. In fact, ylang 
and cananga, a cheaper oil, are derived from the same tree. The 
best ylang ylang oil consists of the first portion of the steam 
distillate. It contains a larger proportion of esters. Cananga 
oil represents the less valuable fractions, forming the second por- 
tion of the distillate. Its odor is not nearly as sweet and its 
value is often less than 10 per cent of ylang oil. It contains 
benzyl alcohol, benzyl acetate, benzyl formate, benzyl benzoate, 
benzyl salicylate, methyl anthranilate, methyl benzoate, methyl 
salicylate, geraniol, geraniol acetate, linalool, linalyl acetate, 
eugenol, iso-eugenol, methyl eugenol, methyl iso-eugenol. This 
list, while long, is by no means complete, as a number of allied 
bodies, especially other esters, are also present. Even all these 
together will not give the right odor, until the characteristic 
constituent is added which converts the product into ylang ylang. 
This body is the methyl ether of para-cresol, which is enormously 
powerful and therefore must be used with great care. Traces 
of para-cresol itself and of guaiacol ethers are also present in 
the oil. 

CUMARINE. Cumarine C 6 H 4 (0)CHCHCO is the active 



ESSENTIAL OILS 351 

principle of tonka beans and is also widely distributed in nature. 
It is found in quantities in the herb known as deer tongue and in 
small proportions is present in hay. The odor of new-mown hay 
in the fields is due partially to this substance. From the chemical 
standpoint, cumarine is interesting, because it can be made 
from carbolic acid or phenol. Phenol, by treatment with 
alkalies and chloroform may be readily converted into a mixture 
of two aldehydes. Ortho-oxy-benzaldehyde b is usually formed 
in the larger proportion and may be readily converted into 
cumarine by the well-known Perkin reaction, by condensing 
this aldehyde with acetic anhydride and anhydrous sodium 
acetate. After proper purification, the chemical so prepared 
cannot be distinguished from a properly purified cumarine 
obtained either from deer tongue or from the tonka bean. 
Purification is of prime importance because the slightest odor 
of the parent material, or of one of the reagents, adhering 
to the finished product will entirely spoil it. Cumarine is 
largely used in making cheap flavors, also in perfumery and in 
scenting soaps. Some of its chemical derivatives, the manufacture 
of which is more complicated, are even more valuable. 

HAWTHORN, AUBEPINE, NEW-MOWN HAY OILS. Para-oxy- 
benzaldehyde is the other aldehyde formed in smaller proportion 
in the reaction just mentioned. While a nearly odorless solid 
it can readily be transformed into the methyl derivative, an oil 
of powerful odor, recalling hawthorn blossoms and known as 
aubepine, CeH^OCH^CHO. New-mown hay perfume oils con- 
tain several derivatives of the constituents just discussed and 
should be mentioned here, as they are so valuable as sweeteners, 
in many perfume formulas. 

BIRCH OIL. Birch oil is almost entirely composed of the 
methyl ester of ortho-oxy-benzoic acid or salicylic acid. This 
is also the main constituent of value in oil of wintergreen. For 
this reason the U. S. Pharmacopoeia has recognized artificial 
methyl salicylate, made by condensing salicylic acid, and methyl 
or wood-alcohol. For flavoring, methyl salicylate is much inferior 
to ethyl salicylate, which also exists in many natural oils, as the 
ethyl ester gives not only a sweeter, but more lasting flavor. 

WINTERGREEN OIL. Oil of wintergreen represents one of 
the exceptions among essential oils, as it consists of practically 
one constituent to which the odor and flavor value is due. Almost 
all others are much more complex in character. Methyl sali- 
cylate, mixed with a little ethyl salicylate, and a trace of the 



352 ELEMENTS OF INDUSTRIAL CHEMISTEY 

methyl ester of methyl salicylic acid, can scarcely be distinguished 
in flavor from the natural oil. It is not surprising, therefore, 
that these natural oils are so largely adulterated, for while the 
synthetic oils are legitimate articles of commerce, they should 
not be supplied where the natural product is ordered, as this is 
much higher in value, due to the cost of production. 

CAMPHOR AND SAFROL. Camphor Ci Hi 6 O is a body 
which, while not an essential oil, is very important, not only on 
account of its medicinal value, but because it is the parent sub- 
stance of many other chemical bodies. Japan has controlled its 
production, but it has also been made by synthesis, and arti- 
ficial camphor is now on the market. Camphor is obtained 
commercially by distilling with steam the wood of the camphor 
tree. Recently, the discovery has been made by the U. S. Depart- 
ment of Agriculture Experiment Stations, that small plants, just 
started from the seed, can be mown and distilled with a very 
good yield of camphor. Camphor is a solid which crystallizes 
from camphor oil on chilling. The crude product is imported 
from Japan and refined in the United States. Camphor oil, the 
liquid portion, is very complex, and is one of the sources of safrol, 
which is used commercially in medicine as artificial oil of sassa- 
fras, of which this is the principal constituent. 

SASSAFRAS OIL. As stated above, safrol C10H10O2 is the main 
constituent of this oil, of which it forms 80 per cent, the balance 
consisting of 7 per cent camphor and terpenes. It finds employ- 
ment in medicine and for scenting laundry soaps. 

Heliotropine and Heliotrope-flower Oils. Safrol is 
also used chemically. By oxidation it yields heliotropine or 
piperonylic aldehyde, CeH3(OCH20)CHO, the methylene deriv- 
ative of protocatechuic aldehyde. This substance has the odor 
of heliotrope and is one of the constituents to which the flower 
oil owes its perfume. Alone, however, it lacks strength and 
character and must be reinforced with other bodies present in 
the blossom. Heliotropine crystals have proven valuable as an 
addition for sweetening soap perfumes and for other technical 
applications. Heliotrope-blossom oils are among the most useful 
products available for perfumery, as they are much used for 
sweetening many other flower odors. 

BITTER ALMOND OIL AND BENZALDEHYDE. The essential 
oil of bitter almond is an illustration of the futility of the classi- 
fication of essential oils according to their botanical origin. The 
almond tree is a member of the great rose family, resembling our 



ESSENTIAL OILS 353 

peach. There is no difference between the bitter and the sweet 
almond trees, and the fruits of both contain a considerable 
amount of fatty oil, which is also utilized in medicine as " oil 
of sweet almonds." A similar oil may be found in the apricot 
and peach fruit, but in addition, these two and the bitter almond 
kernel contain a body called " amygdalin," which is a combi- 
nation of glucose, hydrocyanic acid and benzoic aldehyde, and 
this breaks down into these bodies when acted upon by a fer- 
ment, called emulsin, which is also present in the fruit or seed, 
or by other hydrolizing agents. After the emulsin has acted, 
direct steam is applied, and a very old process in vogue among the 
alchemists, and named by them " cohobation," is employed. The 
water which has been distilled off is returned to the still after 
separating the oil, by which means the total amount of water 
used is kept down to a minimum and a much larger quantity of oil 
is recovered. The hydrocyanic acid must be removed from oils 
intended for flavoring, because it is highly poisonous, and during 
this and the previous handling care must be taken to prevent, 
as far as possible, the rapid oxidation of the principal constituent, 
benzaldehyde, to benzoic acid. 

The oil of bitter almond, deprived of prussic acid, is com- 
mercially known as oil of bitter almond, S. P. A. (without prussic 
acid). The natural oil containing the acid is very poisonous 
and must never be employed, excepting for medicinal purposes, 
when the prescribing physician specially desires its medicinal 
effects. 

ANISE OIL. Anise oil is easily obtained, as it is only necessary 
to steam-distil the seed until the residue is free enough fro n oil 
to be used as cattle food. The resulting anise oil is quite com- 
plex in composition, the main constituent being anethol C10H12O, 
the methyl ether of para-propenyl-phenol, and with it is associ- 
ated the corresponding allyl compound known as iso-anethol, 
methyl chavicol, or estragol C10H12O. These bodies are also 
found in almost the same proportion in an entirely different oil 
from a botanical standpoint, because anise is a member of the 
L^mbelliferous family, to which carrots and parsnips belong, while 
the star anise is distilled in China from the fruit of an ilex tree, 
which is related to magnolia, and yields an oil which can scarcely 
be distinguished by chemical test from true anise oil. Star anise 
oil is usually produced in the crudest ways by natives and is sold 
at a much lower price. The oil is used in medicine and some- 
times as a flavor. 



354 ELEMENTS OF INDUSTRIAL CHEMISTRY 

BAY OIL. Bay oil is in no way related to the bays or laurels 
of classical times, but is distilled from leaves of trees native to the 
West Indies, belonging to the Pimenfca or Myrcia family. At 
early date these sweet leaves were soaked in rum, and the well- 
known bay-rum was the result. It was later found that an oil 
obtained by steam distillation could be added to alcohol, and a 
very similar product obtained. The oil contains eugenol and 
methyl eugenol as its principal constituents. It also contains 
chavicol C6H4(OH)C3H5, and its methyl ether, which has been 
mentioned previously as present in anise oil, and a little citral, 
which we shall consider later. In addition there are a number 
of terpenes, which are bodies that have only recently been inves- 
tigated and about which we shall have much to learn before we 
can understand them. They are present in many oils in consider- 
able proportion and in traces in nearly all essential oils that are 
distilled. They are a disadvantage in practically every instance, 
as they take up oxygen from the air, thicken the oils, give rise 
to unpleasant odors and have but little odor value themselves. 
Many of the natural oils contain a large proportion of terpenes, 
and therefore a purified product which eliminates these is highly 
to be preferred in manufacturing, because the purified oil is more 
soluble, has the odor of the plant or fruit in a higher degree, and 
is more concentrated. 

CITRUS OILS. The oils of the Citrus family, which include 
bergamot, lemon, lime, orange and bitter orange, are made com- 
mercially principally in southern Italy and Sicily. (Oil of orange 
is also made in Jamaica.) All are obtained by expression and 
not by distillation. 

BERGAMOT OIL. Oil of bergamot owes its odor principally 
to the esters present, consisting of linalyl acetate and allied 
compounds. The commercial oil usually contains from 30 to 40 
per cent of ester and is valued according to ester content. It 
has been largely adulterated, especially since the price has risen 
during the last few years, and should be purchased from reliable 
sources. Synthetic products are available, which duplicate the 
odor at considerably less < cost. 

LEMON OIL. Lemon oil consists principally (over 90 per 
cent) of terpenes, which have no flavor or odor value, but which 
hasten the rapid oxidation of the oil, so that lemon oil will not 
keep very long and changes into turpentine-like-smelling deriva- 
tives, which are useless for technical application. The active 
principles of lemon oil consist of about 8 per cent, the main con- 



ESSENTIAL OILS 355 

stituent being citral, the aldehyde of geraniol, which we shall 
further consider under geranium oil. Citral is usually isolated 
from lemongrass oil, in which it is present in far larger proportion, 
ranging from 60 to 80 per cent, according to quality. Lemon- 
grass oil contains, however, other constituents that have a dis- 
agreeable odor. Citral alone, even when pure, does not produce 
a fresh lemon flavor. It is well known that other substances are 
present in small proportion, for instance, small amounts of linalyl 
acetate, methyl anthranilate, and a number of other compounds. 
Lemon oil is used mainly as a flavor. Where a lemon "perfume 
is wanted, as in soaps, citral may be used to much better advan- 
tage at a large saving in cost. 

ORANGE OIL. The oils of bitter and mandarin oranges and 
limes are made on a small scale, but the oil of sweet orange has 
found extended application in flavors and perfumery for many 
years. Oil of sweet orange contains a larger proportion 
of terpenes, which are useless from the odor and flavor standpoint, 
than any of the other oils of the Citrus family. In fact, it is 
estimated that less than one-twentieth of the weight of the 
commercial oil of orange consists of the active odor or flavor- 
bearing portion — among these decoic aldehyde has been identi- 
fied as one of the constituents that contributes the main flavor, 
but many other items are present. 

GRASS OILS. From the citrus oils we pass to the East- 
Indian oils of the Citronella family, which include a number of 
aromatic grasses. They are known by various names, and while 
closely related botanically, produce oils of entirely different 
odor-effects when distilled. They include the oils of citronella, 
palma rosa, or East-Indian geranium, gingergrass, lemongrass 
and vetiver. Hundreds of tons of these grasses are distilled 
annually by the natives in India. 

CITRONELLA OIL. Oil of citronella is mostly used for technical 
applications and for perfuming laundry soaps. Chemically, 
it is a source of the important terpene alcohol, geraniol, a con- 
stituent of rose oil. It also contains an aldehyde, citronellol 
CioHigO, closely related chemically to citral, the aldehyde of 
lemon oil, which serves as a raw material for building up other 
materials by synthesis. 

PALMA-ROSA OIL. Oil of palma-rosa, or East-Indian gera- 
nium oil, is likewise of importance, as it contains a large propor- 
tion of geraniol, which is isolated from the oil chemically and 
finds extended application. The oil itself is used as a soap per- 



356 ELEMENTS OF INDUSTRIAL CHEMISTRY 

fume. Oil of gingergrass, so called up to recent times, was thought 
to be an adulterated palma-rosa oil, but has been proven to be 
a distinct essential oil, distilled from a different species of grass. 
It finds application principally in scenting soaps. 

VETIVER OIL. This oil, also known as cus-cus, kusa or kus, 
is one of the oldest known perfume odors, and still enjoys great 
popularity. It is distilled from the root of Andropogon muri- 
catus or squarrosus, an East-Indian grass. The oil made in India 
is usually distilled with sandalwood, but the root is exported and 
worked up principally in European factories. The yield of oil 
ranges from 0.45 to 0.92 per cent. The Reunion oil is much 
inferior in odor and has a different chemical composition. Even 
the best oil contains some constituents having a disagreeable 
odor, furfural, diacetyl, etc. It is purified chemically and may 
then be used in perfumes of the highest grade. When employed 
in very small proportions it gives a most charming perfume 
effect and the fine character of many modern popular odors of 
the Oriental type is due to this constituent. 

LEMONGRASS OIL. Oil of lemongrass is of great value, 
because this contains, as previously mentioned, a large propor- 
tion of citral CioHieO. Citral is not only one of the active 
principles of oil of lemon to which the main flavor is due, but 
may be chemically converted into other derivatives which are 
of much greater value in perfumery. Citral may be condensed 
with acetone, by any alkaline-condensing agent, forming a ketone 
derivative known chemically as pseudo-ionone, which by treat- 
ment with acids is converted into ionone. Many isomeric sub- 
stances are produced commercially and find extended application. 

IONONE. Ionone C13H20O is a direct derivative of the 
benzene series. The acid treatment converts the chain formula 
of the aliphatic series into an aromatic derivative by closing the 
chain into a benzene ring. Ionone exists in a number of isomeric 
forms, each of which has a slightly different odor. Many deriva- 
tives of ionone have been made. The name " ionone " having 
been trade-marked at the time the original patent (now expired) 
was applied for, in 1893, these violet ketones are marketed under 
various trade names, as iovionol, neoviolone, ional and many 
others. This has caused some confusion, as different products 
are marketed under the same name. For instance, iralol has 
been used erroneously for ionone, but properly refers to methyl 
ionone, a constituent of artificial orris oil. The conversion of 
pseudo-ionone by means of acid gives rise to many impurities 



ESSENTIAL OILS 357 

having a disagreeable odor. Consequently these ketones are 
on the market in all possible qualities, from those which are 
almost useless, on account of imperfect purification, to products 
which have a charming floral odor and are applicable for the 
finest perfumery purposes. Ionone is an isomer of irone, the 
active principle of the essential oil of orris root. 

ORRIS OIL. Orris root, or the iris of Italy, when distilled, 
yields an essential oil containing about 90 per cent of myristic 
acid and about 10 per cent of active perfume substances of which 
irone C13H20O is the main constituent. An absolute orris oil 
free from the fatty acid is also sold, being from 8 to 10 times as 
strong. Methyl iovionol or iralol C14H22O is a basic ketone 
having a very sweet and powerful orris odor. Other synthetic 
orris products are available which even duplicate the valuable 
fixing properties of the root and are entirely free from the odor- 
less myristic acid found in the natural oil. 

VIOLET ODORS. Ionone, as well as irone, popularly repre- 
sents the violet odor, but as a matter of fact many other sub- 
stances contribute to the violet perfume. The manufacturer who 
thinks he can get a violet by merely dissolving a basic ketone 
like ionone, iovionol, iralol, irone or orris oil in alcohol is doomed 
to disappointment, because the other substances are missing 
which contribute the life-like character and really produce the 
complex odor-effect which the public knows as violet. 

CASSIE OR ACACIA ODORS. These blossom oils belong to 
the violet series, but contain as added constituents the methyl 
esters of salicylic and methyl salicylic acids, methyl-eugenol and 
other bodies. Both natural and synthetic blossom products are 
available, which are used extensively and have a most delightful 
flower perfume. Mimosa also belongs to the cassie type perfumes. 

SANDALWOOD OIL. Oil of sandalwood has been known for 
many years and has always been highly esteemed in the Orient. 
Sandalwood itself is an ancient constituent of incense, and the 
trade in this rare w T ood is so valuable that it has been monopolized 
by the Indian government, auction sales being held at regular 
periods, under supervision of East-Indian officers. But little of 
the wood is distilled in the Indies; the greater part is exported 
to Europe and America, where the oil is produced by modern 
methods. The principal portion of the oil is known as santalol, 
a rather complex chemical substance which is both alcoholic and 
aldehydic in nature and consists of a number of distinct chemical 
individuals. 



358 ELEMENTS OF INDUSTRIAL CHEMISTRY 

SANTALOL. Santalol is much more valuable to the perfumer 
than sandalwood oil because it represents only the useful por- 
tion of the oil, as the ill-smelling constituents have been removed. 
From some of the fractions of sandalwood oil, the writer suc- 
ceeded in isolating portions which have odors almost identical 
with certain fractions obtained from oil of patchouly, showing 
that these oils, produced in the same climate by a tree and herb 
which have no botanical relation, contain similar compounds. 

CEDAR OIL. The cedar-like odor of oil of sandalwood ,has 
often led to its adulteration with oil of cedar, which is much 
cheaper and may be had in unlimited quantities. Much cedar- 
wood oil is distilled from the sawdust or shavings produced in 
manufacturing lead pencils. A finer grade finds a limited market, 
being used in microscopical work. 

JUNIPER OIL. Cedar is a member of the Juniper family. 
Juniper berries and their oil have long been used for making gin 
and for flavoring. The berries have also a historical interest, 
since in some sections of Central Europe the custom prevails, 
when a death occurs in a house, of roasting the berries in a red- 
hot pan, so as to have the odor diffused throughout the rooms. 
Apparently this is a tradition which has been handed down 
from pagan times, since juniper berries formed part of the sacri- 
ficial offerings of the early Teutons. 

TURPENTINE OIL. Juniper oil contains a considerable 
proportion of terpene, and this brings us to the field of turpentine 
and allied products. Turpentine is a widely used solvent and is 
becoming scarcer each year, so that lately even the old stumps 
have been utilized to produce a cheap grade. While not a per- 
fume material, the oil is certainly an essential oil and it also 
serves as a source for some constituents of our most valued 
flower odors. 

TERPINEOL AND DERIVATIVES. Turpentine may be hydrated, 
forming terpene hydrate, which in turn, by treatment with acids, 
may be converted into terpineol. This is a terpene alcohol which 
exists in many of the finest flower oils, though in numerous modi- 
fications, widely varying- in physical properties, opcical rotation, 
boiling-point and melting-point and differing just as widely in 
odor. The common terpineol, much used as a soap scent, is a 
sirupy oil looking like glycerine. Purified products are also 
marketed and are invaluable in fine perfumery. (Terpineol 
Blanc, Muguet, Muguet Blanc, Muguet Ideal, etc.) Isomeric 
modifications of terpineol are present in lilac, tuberose, mimosa, 



ESSENTIAL OILS 359 

ylang ylang, lily of the valley, and many other exquisite flower 
oils. 

LILAC-FLOWER OILS. Terpineol bears the same relation to 
these very popular blossom oils as geraniol to oil of rose. Lilac 
flowers contain many of the other chemical constituents we 
have already described. Lilac-flower products are obtainable 
in many shadings of this odor suitable for many different purposes. 
The so-called French lilac is merely a variation combining lilac 
and hyacinth odors. 

EUCALYPTUS OILS. In Australia we find various members 
of the Eucalyptus family. They yield oils differing very much 
in chemical composition and odor, and the exact species of tree 
from which the oil was obtained should always be mentioned. 
The ordinary commercial eucalyptus oil owes its medicinal effect 
principally , to a body chemically known as eucalyptol or cineol 
CioHisO. Eucalyptol is widely distributed throughout the 
essential oils in small proportion, but when present in large 
proportion, as in eucalyptus oil, or when concentrated, it has 
a disagreeable taste and odor. Consequently its use has de- 
creased considerably in recent years, as other medicinal bodies 
have been found which are not as unpleasant. 

PELARGONIUM OR GERANIUM OIL. Oil of pelargonium is 
one of the more modern oils and is of considerable commercial 
importance, as it contains about 70 per cent of terpene alcohols, 
that is, both geraniol and citronellol, in varying proportions, 
according to the source. It shows that the same plant will 
yield other chemical substances w T hen grown in different soils or 
climates. A number of varieties of pelargonium or geranium are 
distilled in Algeria and throughout northern Africa, as well as 
in some of tne French islands, especially Reunion, and to a limited 
extent in southern France. The plant is common with us as a 
house-plant, and is known as " rose geranium." The oil is used 
in perfumery and soap-making, and also serves as the source 
of the valuable terpene alcohols, which may either be isolated 
and used as such or changed by synthesis into derivatives having 
a muctThigher perfume value. The so-called Turkish or East- 
Indian geranium oil should not be confused with these pelar- 
gonium oils, as it is distilled in the East Indies from one of the 
grasses. See under palma-rosa oil. 

LAVENDER OIL. Oil of lavender is distilled from a member 
of the mint family, and while quantities are produced in England, 
the bulk of the product comes from southern France. French 



360 ELEMENTS OF INDUSTRIAL CHEMISTRY 

lavender oil is commonly valued by the ester content, estimating 
the mixture of esters as linalyl acetate. The so-called Mitcham 
or English lavender oil contains less ester, but other constituents 
are present in small proportion which give a different perfume 
effect. The English oil commands a higher price. This is again 
an instance where the proportion of one constituent does not de- 
termine the value of a perfumery product. It is the quality of 
the constituents present that influences the value of the oil. 
Synthetic products are also marketed which impart a similar 
perfume to the English oil. 

CLOVE OIL. Cloves, one of the earliest items of trade be- 
tween the East and West, contain such a large proportion of oil 
that even the crudest methods give a fair yield. Cloves are the 
dried, unopened flower-buds of a beautiful evergreen tree. Clove 
oil is the commercial source of eugenol, which chemically is allyl- 
methoxy-oxy-benzene C10H12O2. This is present in the com- 
mercial oil to the extent of from 70 to 85 per cent. The other 
constituents are of no commercial importance. Eugenol may be 
obtained from clove oil by combining it with an alkali, removing 
the terpenes, setting free the eugenol, and vacuum, distilling. 
Its specific gravity increases on aging, owing to the formation of 
resinous or condensation products. Consequently, a perfectly 
pure material, when freshly distilled, will have a slightly lower 
specific gravity. By treatment with alkalies, eugenol may be 
converted into iso-eugenol, which on oxidation yields vanilline. 

VANILLINE. Chemically, vanilline C 6 H 3 (OH) (OCH 3 )CHO 
is the methyl ether of protocatechuic aldehyde and forms one of 
the main flavoring constituents present in vanilla beans. Vanil- 
line alone, however, will not duplicate the entire flavor of vanilla, 
as it merely represents one of the constituents of the bean flavor. 
Vanilla beans contain in addition to vanilline other substances 
to which the fine flavor of the beans is principally due. Popularly, 
and quite erroneously, it has been thought that the resinous 
substances which are present contribute to the flavor. As a 
matter of fact, the resinous bodies in the bean, when separated, 
tenaciously hold a small proportion of the active principles, but 
when perfectly pure, these resins have practically no odor or flavor- 
ing value. Synthetic materials are available, however, which 
duplicate the entire flavor of the finest beans and are free from 
resins or tannins which contaminate the natural bean flavor. 

Allspice Oil (or Pimento). Another oil which contains 
a considerable proportion of eugenol (65 per cent) is the oil of 



ESSENTIAL OILS 361 

allspice or pimento, official in the U. S. Pharmacopoeia. It is 
used principally for flavoring. Most of the spices, herbs and other 
condiments utilized owe their flavoring value to essential oils. 

HERB AND SPICE OILS. Among these, we may mention the 
oils of mace, nutmeg, caraway, celery, coriander, cumin, fennel, 
ginger, marjoram, parsley, sage, thyme, and pepper, all of which 
are more or less complex in composition. Space does not allow 
their discussion in detail. 

CASSIA OIL. Another spice oil of importance is oil of cassia, 
improperly called in the U. S. Pharmacopoeia, VIII revision, oil 
of cinnamon. Oil of cassia owes its main value to cinnamic 
aldehyde CeHsCHiCH.CHO, which is present to the extent of 
about 80 per cent. This aldehyde is also produced by synthesis 
by condensing benzaldehyde with acetic aldehyde. 

CINNAMON OIL. Ceylon cinnamon oil is worth about four 
to five times as much as oil of cassia. It has a finer odor than 
cassia, and while the content of cinnamic aldehyde is lower, 
ranging from 65 to 70 per cent, other constituents are present 
which influence the odor considerably. For this reason Chinese 
cassia oil and Ceylon cinnamon oil should not be confused or 
called by the same name. The odor of cassie also should not be 
confused with cassia. Cassie is a member of the acacia and 
mimosa family and belongs to the violet group of odors. See 
Blossom Oils. 

PEPPERMINT OIL. While speaking of the aromatic oils 
used as condiments or for flavoring, we must not overlook pepper- 
mint, which is produced so extensively in America. Oil of 
peppermint owes its chief value to menthol, an alcohol, having 
the formula C10H19OH, and some of the esters of menthol, prin- 
cipally menthol acetate. Japanese oil of peppermint is also mar- 
keted, though often part of the menthol has been previously re- 
moved from it. 



CHAPTER XVIII 
RESINS, OLEO-RESINS, GUM-RESINS AND GUMS 

SOURCE. These products are all derived from exudations of 
plants and as a rule are oxygenated bodies. When mixed with 
certain percentages of the natural essential oil accompanying 
them, they are known as oleo-resins or balsams. If mixed with 
mucilaginous matter they are harder and known as gum-resins. 
Gums are amorphous bodies which are either soluble in or gelatin- 
ize with water, but are insoluble in alcohol. True resins are 
distinguished from gums in that they are all insoluble in water, 
free from odor or taste, form compact masses, and are usually of an 
aldehydic or acid nature. Fossil resins are found in the earth, 
usually in the form of irregular lumps, and often contain perfect 
specimens of fossil insects and leaves. 

AMBER. Amber is a fossil resin occurring as small masses in 
alluvial deposits in various parts of the world. According to 
Goefert, it represents the resinous exudation from about fifty 
different kinds of coniferous trees. It is found chiefly in Prussia 
along the shores of the Baltic, where it is thrown up by storms, 
or in some localities is even mined. Large deposits also occur 
in some of the lakes on the eastern coast of Courland. Small 
deposits have been found in New Jersey and Maryland, but not 
of sufficient magnitude to be of commercial importance. The 
largest single mass of amber ever reported weighed thirteen 
pounds. It is usually associated with lignite and often contains 
the fossil remains of insects and vegetation. 

Amber is a brittle solid, permanent in the air, and is suscepti- 
ble to a very high polish. By application of friction it becomes 
negatively electrified. Its color is usually from light to deep 
brownish yellow, although it sometimes possesses a reddish brown 
or bluish color. It is tasteless and odorless when cold, but 
gives off a peculiar aromatic odor when heated. It is generally 
translucent, though sometimes transparent or opaque. It is 
scarcely acted upon by water or alcohol. When heated in the air, 
it softens and finally melts at 286° C, which property makes it 

362 



EESIN8, OLEO-RESINS, GUM-RESINS AND GUMS 363 

of value in the manufacture of varnish. When subjected to 
distillation several products result, among them being succinic 
acid, esters, and oil of amber. Amber is used in making high- 
grade varnish and finds extensive application in the manufacture 
of tobacco pipe stems and articles used for ornamental purposes. 

ANIME. The substance known as gum anime is a resin 
supposed to be derived from the Hymencea courbaril, a leguminous 
tree of South America. The resin exudes from wounds in the 
bark and is also found under ground between the principal roots. 
It occurs in small, irregular pieces of a pale yellow color, sometimes 
being of a reddish cast. It softens in the mouth, and when in a 
powdery condition adheres to the fingers. It readily melts on 
being heated, giving off an agreeable odor. It consists of two 
resins, one being soluble in cold alcohol and the other insoluble, 
and a small amount of volatile oil. Anime was formerly used 
to quite an extent in the preparation of ointments and plasters, 
but at present is only employed as incense or in the manufacture 
of varnish. 

BURGUNDY PITCH. When incisions are made in the Nor- 
way Spruce a sap exudes which is collected in small troughs, or 
holes dug at the foot of the tree. It is purified by filtering 
through straw and allowed to harden, subsequently being boiled 
with water to remove the volatile oil. 

Colophony or Common Rosin. This product is obtained 

in the preparation of oil of turpentine from crude turpentine. 
The latter is an oleo-resin obtained as an induced exudation from 
the pine tree. The sticky viscid liquid or crude turpentine is sub- 
jected to steam distillation, whereby about 17 per cent of the vol- 
atile oil of turpentine passes over, leaving a resinous matter, or 
rosin, in the still. Many grades of rosin are found in the market, 
being distinguished by letters (W.W. — water white) to designate 
their purity. It is also quoted as virgin, yellow dip and hard. In 
its purest state rosin is beautifully clear, possessing a yellow color 
with an olive tinge. This is obtained from the first runnings 
after the tree is " boxed:' The greater part of the rosin, however, 
comes under the head of yellow dip, which is obtained by distil- 
lation of crude turpentine. The hard rosin is very dark in color 
and is obtained from the scrapings after the juice has become too 
thick to run into the box. 

Rosin is heavier than water, having a specific gravity of 1070 
to 1.080; it is easily fusible, becoming soft at 100° C, m.elts 
to a liquid at 152.5° C, gives off bubbles of gas at 157.5° C. and 



364 ELEMENTS OF INDUSTRIAL CHEMISTRY 

is decomposed at red heat. It is soluble in alcohol, ether, benzol, 
carbon disulphide, acetic acid, fixed or volatile oils, and in solutions 
of potassium or sodium hydroxide. When distilled in vacuo, 
rosin undergoes very little decomposition ; but if heated in a retort 
it yields gaseous liquid and solid decomposition products. That 
portion of the liquid distillate boiling below 360° C. is known as 
rosin spirits, resembling turpentine very closely, for which it is 
largely used as a substitute. The portion distilling above 360° 
C, known as rosin oil, is much heavier and darker than rosin 
spirit and must be purified before use. This purification is accom- 
plished by treatment with sulphuric acid, followed by lime water 
and then distillation. 

COPAL. This is a resinous substance derived from the exuda- 
tion of several varieties of trees indigenous to the East Indies 
and South America, as well as parts of Africa, the Philippine 
Islands and other places. The gum is sometimes taken directly 
from deposits on the tree or is found imbedded in the earth. That 
variety of copal .known in commerce as gum Zanzibar is found 
usually under the ground. Another variety with indented goose- 
flesh surface, known in the English market as anime, is dug from 
the earth. 

Copal varies in appearance and properties, depending upon 
the source from which it is derived. It appears in roundish, 
irregular, or flattish pieces, often with a rough indented surface, 
due to sand impressions while it was in a soft condition. In color 
it ranges from colorless to yellowish brown; it is more or less 
transparent, very hard, odorless, tasteless, and has a specific 
gravity of from 1.045 to 1.130. It is insoluble in alcohol, partly 
soluble in ether, and slightly soluble in oil of turpentine. When 
heated it melts, giving off gases to the amount of 15 to 20 per cent 
of its weight. Its properties are changed by this treatment so 
that it becomes more soluble in alcohol, ether, and oil of tur- 
pentine, which characteristic renders it, like other resins, suit- 
able for the preparation of varnish. 

DAMMAR. This is a resin which exudes in drops from a 
coniferous tree, Agathis loranthifolia, and is collected after it 
dries. It is soluble in essential oils, in benzol, and to a slight 
degree in alcohol and ether. Owing to its light color and ready 
solubility in turpentine it finds extensive application in the manu- 
facture of light-colored transparent varnishes. 

DRAGON'S BLOOD. This is a resinous substance obtained 
from the fruit of several species of small palms growing in Siam, 



RESINS, OLEO-RESINS, GUM-KESINS AND GUMS 365 

the Molucca Islands, and other parts of the East Indies. An 
exudation appears on the surface of the ripe fruit, which is sepa- 
rated by rubbing, by shaking in a bag, by exposing to steam, or 
by decoction. The finest product results from the first two 
methods. It comes on the market in two forms: either as small 
oval drops (tear dragon's blood) covered with the leaves of the 
plant and connected in a row like beads; or in cylindrical sticks 
eighteen inches long and about half an inch in diameter, covered 
with palm leaves and bound with slender strips of cane. An 
inferior product, prepared by boiling the fruit in water, is in the 
form of flat circular cakes (cake dragon's blood) . 

Dragon's blood is odorless, tasteless, insoluble in water, but 
soluble in alcohol and ether, also soluble in the volatile and fixed 
oils, forming red solutions. Its principal use is in the coloring 
of varnish. , 

ELEMI. This resin is obtained by making incisions into the 
trees, through which the juice flows and concentrates on the 
bark. Elemi comes on the market either as soft (Manila elemi) 
or hard (Brazilian elemi) , being of various colors, from light yellow 
to greenish white. It is soluble in alcohol and other solvents, 
its chief use being to impart toughness to varnishes made from 
harder resins. 

GUAIACUM. This resin is the concrete juice of the tree 
Guaiacum sanctum, obtained by several different methods. The 
simplest method is that of spontaneous exudation, or by making 
incisions in the trunk. Another method is to saw the wood into 
blocks, boring holes in them longitudinally, placing one end of 
the block in the fire and collecting the melted resin, which flows 
out at the opposite end. The plan most commonly used, how- 
ever, is to boil the chips and sawdust with a solution of common 
salt, and skim off the substance which rises to the surface. Guaiac 
appears in the market as irregular lumps, often mixed with small 
fragments of bark and sand. The purest form comes in small 
lumps, " tears," which result from natural or induced exudation. 

KAURI. This is an amber-like resin, varying from light 
cream to brownish yellow in color. It is the result of exudation 
from the tree Agathis australis, and is dug in large quantities 
from the ground in New Zealand. It is used very extensively 
in varnish-making, and like copal must be first heated or " run " 
before it becomes soluble in oils. 

MASTIC. This is a resinous exudation from the Pistacia 
lentiscus, a tree cultivated in the Grecian Archipelago. Incisions 



366 ELEMENTS OF INDUSTRIAL CHEMISTRY 

are made in the trunk and large branches, from which the juice 
on exuding either hardens on the bark in tears or drops to the 
ground, where it is caught on cloths. It is of a light yellow 
color and nearly odorless. It is soluble in alcohol up to about 
90 per cent, and is used to quite an extent in the preparation of 
spirit varnish. 

SANDARAC. This resin resembles mastic very closely and 
comes on the market in the form of tears. It is more soluble in 
alcohol, however, and is employed largely in the preparation of 
transparent varnish. 

OLEO-RESINS. The most important members of this class of 
compounds are Benzoin, Peru, Tolu, and Storax. They are all 
mixtures of resins with essential oils, and consequently have a 
much softer consistency than the resins. They are used espe- 
cially in pharmacy, and having practically no industrial applica- 
tion will not be considered in detail in this chapter. 

GUM-RESINS. The more important members of this class 
are Ammoniacum, Asafoetida, Euphorbium, Galbanum, Gamboge, 
and Myrrh. They are mixtures of gums and resins, form emul- 
sions with water, and are all largely used in pharmacy, gamboge 
being also employed as an orange-red pigment. 

ACACIA. Both Gum Arabic and Gum Senegal are included 
under this head, as they are derived from plants of the acacia 
family usually found in Africa. It forms lumps of various size, 
with color ranging from white to reddish brown. It is soluble 
in both cold and hot water and is used in the preparation of 
emulsions, in thickening ink, in water-colors, textile printing, 
sizing cloth, and in the preparation of mucilage. 

AGAR-AGAR. This is also known as Bengal isinglass and 
Japan isinglass. It is derived from certain algae, from which it 
is obtained by boiling in water. It comes on the market as long 
white masses. It is used as a sizing for cloth and as a culture 
medium for bacteria. 

ICELAND MOSS AND IRISH MOSS. These are derived from 
a form of seaweed which on boiling with water produces a jelly, 
much used in the textile and leather industries as well as for edible 
purposes. 

TRAGACANTH. This is a gummy exudation from Astragalus 
gummifer. It is odorless, nearly tasteless, and of a very light 
yellowish to white color. It usually comes into the trade in a 
flaky condition. Placed in water, it absorbs a certain amount 
and swells up very much, forming a soft adhesive paste. If the 



RESINS, OLEO-EESINS, GUM-RESINS AND GUMS 367 

paste is agitated with more water, it forms a uniform mixture, 
which, however, will settle out on standing, as only part of the 
gum goes into solution. It is largely used in calico-printing 
and for other purposes where an adhesive is required. 

SHELLAC. A distinction should be made between shellac 
and lac. Lac is derived from the Indian term for 100,000 and is 
significant of the myriad or swarm of insects taking part in its 
formation. It has been erroneously stated that lac is the dried 
exudation of a tree, caused by the sting of the lac insect, and is 
similar to rosin in its origin. As a matter of fact, it is the secre- 
tion of the lac insect, and is a product of the assimilation of the 
tree sap which the insect feeds upon, just as honey and beeswax 
are produced by the modification of the nectar of flowers by the bee. 

Shellac is so called because of its shell-like form, and bears 
the same relation to lac that flour bears to wheat. It is a manu- 
factured article, and may be manipulated and adulterated, 
whereas lac is the original resin as gathered from the trees, and 
cannot be sophisticated. 

Lac is found only in northeastern India and, to a small extent, 
in the adjacent sections of Assam and Burmah. The shipping 
point is Calcutta. The insect producing lac belongs to the 
scale family (tacchardia lacca), and in the larval form when 
hatched is about one-fortieth of an inch in length and of a red 
or orange color. It has six legs, but no wings, and is too small 
and weak to travel far. It crawls or drops to another twig in 
the vicinity, but thousands are unsuccessful, through their 
inability to find a favorable position or a suitable soft, sappy 
twig which they can pierce with their beaks. As soon as the 
insect comes to rest it immediately begins to suck up the sap 
like an animated siphon, and secretes a substance which soon 
dries around it in contact with the air. They take up positions 
adjoining one another so that as the cells surrounding the insects 
grow larger they eventually coalesce, forming an incrustation 
around the twigs several times as thick as the twigs themselves. 
The formation of the lac is undoubtedly designed as a protective 
coating to shield the insect from its many enemies. Monkeys, 
ants and squirrels feed on the sweet incrustation. Heavy rains, 
hail storms, droughts, and forest fires work at times serious 
injuries. 

About two and a half months after the period of swarming 
the male insect matures, and after pushing up the lower edge of 
its cell crawls out backwards. The female stays in place. The 



368 ELEMENTS OF INDUSTRIAL CHEMISTRY 

female is provided with three tufts of filaments covered with a 
white powder. As the lac gathers around, these filaments act 
as tubes to supply air and to permit fertilization by the male, 
who then dies. The female lives about three and a half months 
longer, continuing to feed on the sap. For this reason the female 
cells are larger than the male cells, and may be recognized when 
a cross-section is made. About a thousand eggs are developed 
by each female, and by the time these eggs are hatched the 
mother has dried up, leaving only the skin. The new brood 
escape from the body of the parent by the air-ducts in the lac, 
and another life-cycle begins. There are two generations each 
year, the swarming taking place in July and December. Lac 
may be propagated by cutting off the swarming twigs and tying 
them to the branches of healthy trees. 

Stick-lac. The in crusted twigs are broken into short sections 
and constitute the stick-lac of commerce. The lac is gathered 
twice a year by the natives. It is brought to some central point, 
such as Mirzapore, where it is hand-picked and graded. The 
principal trees bearing lac are the Kusum and Palas, but some 
eighty-eight varieties of trees have been recognized as hosts 
for the lac insect. The kind of tree and the nature of the 
sap fed on, as well as climatic influences, are undoubtedly fac- 
tors in the value of the product. Almost nothing is known of 
the origin of the various varieties of stick-lac. 

Seed -lac or grain-lac is produced from stick-lac by crushing, 
washing, and drying. In this way the wood and a considerable 
part of the coloring matter is removed. Seed-lac consists of ruby- 
red or orange-colored grains about the size of wheat. 

Lac Dye. If the wash-water from the stick-lac is allowed 
to settle, lac dye deposits. Before the advent of the synthetic 
dyes large quantities of this material were shipped to Europe 
(1,544,480 lbs. in 1880), where it was used as a substitute for 
cochineal. The trade has now entirely disappeared and lac dye 
is only seen as a curiosity. 

Shellac. To make shellac the workman fills long, narrow bags 
with dry seed-lac, to which a certain quantity of orpiment, and 
sometimes rosin, is added. The bag is heated over a charcoal 
fire until the lac has fused and run through the cloth. By twist- 
ing the bag the molten lac is forced out and is scraped off with a 
metal hook. It is flattened out by stretching over a cylinder 
filled with hot water. It is then reheated, clasped between the 
feet and hands, and pulled out into a thin sheet of a light to dark 



RESINS, OLEO-RESINS, GUM-RESINS AND GUMS 369 

orange color. In good grades any imperfections are flecked out 
of the sheet by the finger. The edges are broken off and retnelted 
in the better grades. 

The sheets are broken into flakes and packed for shipment. 
This is the form in which lac is commonly seen, and is the material 
for sale in the paint store. 

Caoutchouc or India Rubber. India rubber is the 

coagulated product obtained from the milky juice of a large 
number of trees, creepers and shrubs native of nearly all tropical 
countries, although the finest grades (Para rubber) come from 
South America. The juice is collected during the months of 
July, August, October and November. It is coagulated by 
exposure in thin layers to the smoke of burning palm nuts, or 
it is boiled with water, with dilute acid, salt water, with lye, or 
with alum. , 

As rubber comes on the market it is very impure, containing 
water, sand, fibers, wood and various other materials. These 
impurities are removed by a washing process which is carried out 
in strong machines built for the purpose, consisting of corru- 
gated rollers, which flatten the lumps into thin sheets, thus aiding 
in the washing process. The sheets thus obtained are dried very 
thoroughly by hanging in a warm room for several weeks. 

Chemical Properties. Commercial washed rubber has a resin 
content varying from 1 to 10 per cent and 15 per cent. These 
resins are soluble in boiling aceton. Volatile organic solvents, 
such as turpentine, carbon disulphicle, benzol and petroleum 
naphtha, cause a swelling of the rubber to a jelly-like mass. This 
becomes distinctly viscous on further dilution; in fact, Fol of 
Delft has endeavored by numerous experiments to show the 
relation between viscosity, resin content, and strength in crude 
rubber. The most important chemical property is without doubt 
the fact that rubber combines with sulphur in all proportions up 
to a product containing about 32 per cent of sulphur. This 
combination of rubber with sulphur is known in practice as " vul- 
canization." 

Physical Properties. The physical properties which give 
rubber its value as a material of commerce are: (1) Its pale color; 

(2) high tensile strength, high adhesion and cohesion values; 

(3) great elasticity; (4) pliability; (5) impermeability to water 
and gases; (6) enormous dielectric value; (7) the ability to " take 
up " powdered minerals and form with them a homogeneous 
mass; (8) low specific gravity. 



CHAPTER XIX 
VARNISH 

DEFINITION. Varnish is a liquid designed to form films to 
cover surfaces, which on exposure to the air hardens and forms a 
more or less transparent and glossy coating, which improves or 
better displays the surface to which it is attached and to some 
degree protects it from dirt and injury. 

CLASSES OF VARNISH. Varnishes may be divided into two 
classes : those which harden by evaporation of the solvent — such 
are spirit varnishes, and those which absorb oxygen from the 
air and by chemical changes are made into hard films; these are 
oleo-resinous varnishes, and constitute the largest, most impor- 
tant and varied kind, used for a great variety of purposes. 

SPIRIT VARNISH. Spirit varnishes consist of suitable solids 
dissolved in volatile solvents. The most important is shellac, 
which may be regarded as typical. It consists of shellac resin 
dissolved in alcohol, and when spread out in a film the alcohol 
evaporates, leaving the resin as a thin layer over the surface to 
which the varnish has been applied. It will be evident that the 
alcohol has served practically as a mechanical means of spreading 
the resin in a thin and uniform film. Its cost is to be added to 
that of the labor and the use and wear of utensils required in 
applying the varnish, as all that we have at the end of the work 
is the film of resin. 

SHELLAC VARNISH. Gum-shellac, as the shellac resin is 
called, is usually in thin elastic flakes of a yellow or reddish or 
brownish-yellow color. Put a gallon of alcohol in a clean earthen- 
ware jar of two gallons capacity; at the close of the day's work 
gently drop into this three or three and a half pounds of flake 
shellac, without the slightest avoidable agitation; cover and let 
stand until the next day. Then with a clean wooden rod stir 
it for a few minutes, and during the day stir it for a minute at 
a time once an hour or so, and before night it will be dissolved. 
That is, the resin will be dissolved ; but shellac naturally contains 
a little wax (4 per cent) which is insoluble and makes the solution 

370 



VARNISH 371 

milky or muddy and opaque; the film is, however, transparent. 
Shellac may be bleached by dissolving it in an alkaline aqueous 
solvent and then treating it with chlorine; the shellac precipitates 
when the alkalinity is removed, and is white. This is dried and 
looks much like pieces of white candy; it cannot be dissolved in 
the manner described, as it is in lumps and sinks to the bottom; 
it is therefore dissolved by agitation, usually in a revolving barrel 
or churn; this is indeed the way orange shellac is made on a large 
scale. The latter is soluble in 85 per cent alcohol, though it is 
more satisfactory to use stronger; but w r hite shellac already con- 
tains some water and requires 95 per cent alcohol. 

INSOLUBLE SHELLAC. White shellac is liable to pass into a 
modified form insoluble in alcohol; this especially is likely to occur 
if heated above ordinary temperatures or if kept in a dry place 
too long. ( For some purposes it is desirable to get rid of the 5 
to 10 per cent of water in white shellac before dissolving it; it 
is spread on trays in a drying room, but not heated very much; 
it is better to use artificially dried air at ordinary temperatures; 
in any case it must be dissolved as soon as possible. 

Shellac varnish dries by the evaporation of the solvent, and 
appears to dry almost immediately; but some of the liquid is 
retained for a time, and it is not practicable to apply many coats 
in rapid succession, or it will be found that the whole has a waxy 
character, persistent and troublesome. Varnish made with 
" denaturized " alcohol is especially slow to dry; commercial 
wood alcohol is much better. 

DAMAR VARNISH. Alcohol is not the only solvent used in 
making spirit varnishes. Damar varnish is damar resin dis- 
solved in spirit of turpentine, and dries by the evaporation of 
the latter. Both this and shellac are often adulterated with 
common rosin or colophony. Damar may be dissolved cold 
in a churn; some pulverize it before dissolving, or make it with 
the aid of heat, preferably in a steam-heated vessel. The varnish 
is a milky liquid, but may be cleared by filtration or otherwise. 
If made hot it can be cleared more easily. Five or six pounds 
of resin are dissolved in one gallon (7-J lbs.) of spirit of turpen- 
tine. The film is transparent and practically colorless. 

Mastic and Sandarac Varnish. Sandarac is another 
resin usually dissolved in spirit of turpentine; another is mastic; 
both are also mostly soluble in alcohol. Amyl and methyl 
alcohols are for some resins better solvents than ethyl alcohol; 
and acetone added to alcohol greatly increases its solvent power. 



372 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Petroleum benzine is very commonly added to turpentine to 
cheapen it; it has the advantage of evaporating more readily 
and perfectly, and some of the heavier grades are for many pur- 
poses equal and perhaps superior to turpentine. 

PYROXYLIN VARNISHES. Pyroxylin varnishes are a variety 
of spirit varnishes. The solid part is cellulose, rendered soluble 
by acting on it with nitric acid, making cellulose, nitrates of 
various compositions. The principal solvent is amyl acetate, 
which may be extended or diluted with various liquids, as benzol, 
which have no real solvent action on the pyroxylin, but do not 
inhibit the solvent action of the amyl acetate, differing in this 
respect from the action of water on alcohol. Pyroxylin films 
are somewhat hard and stiff, and may be made more flexible by 
adding a fixed oil, as castor, cotton or linseed, to the solution. 

LACQUER. Spirit varnishes are often called lacquers, and 
are sometimes colored by aniline or other dyestuffs. Both 
asphaltum and coal-tar pitch are soluble in turpentine and benzene, 
or coal-tar naphtha, and are used as spirit varnishes; but more 
often with the addition of oil. Rosin is almost always added to 
asphaltum, but not necessarily. 

OLEORESINOUS VARNISHES. The greater part of the varnish 
made is compounded of oil, resin, and spirit of turpentine, and is 
of great variety of composition and uses. Almost all the oil 
used is linseed. A little tung or Chinese wood-oil is used, but 
inconsiderable in amount as compared with linseed. This oil is 
usually subjected to some preliminary treatment. It is as pur- 
chased from the makers well settled and filtered and free from 
cloudiness. It may be remarked that a mere trace of water 
causes a cloud, and the not uncommon belief that oil must be 
freed by some treatment from water and " mucilage " is a mis- 
take, as oil of ordinary good quality is quite free from such things. 

BREAKING. Freshly made oil if heated to 400° F. suffers 
a slight partial decomposition; gelatinous clots appear in it, and 
it is said to " break"; this is due to the phosphates it contains, 
and any treatment which will destroy these will prevent its 
" breaking." A common way is to add with agitation a little 
sulphuric acid; the oil is afterward washed with water, and is 
found to be bleached somewhat; it may be bleached more by 
agitating warm with fuller's earth and filtering; but not all the 
color can be removed by any known means. What is known 
as " varnish oil " has been treated in some way so that it does 
not break; and if such oil is heated quickly to about 500° F. and 



VARNISH 373 

cooled, it is found to be considerably bleached. This is a com- 
mon practice. Sometimes a very little of some lead or manganese 
compounds are added before doing this. It is usually put 
through some such treatment and allowed to settle for a month 
or more before being used in varnish. 

WEIGHT OF OIL. A gallon of linseed oil weighs 7.75 lbs.; 
but in selling oil by the barrel or larger quantities it is a com- 
mercial practice to call 7.5 lbs. a gallon, so that in buying it one 
gets about 3 per cent less in fact than the nominal amount. No 
charge, however, is made for the barrel — an oil-barrel is usually 
a 50-gal. cask— the value of which is usually more than the 1J 
gallons lacking. In making paint or varnish the full weight or 
measured gallon is always the unit. 

RESINS. Asphaltum is a mineral, but practically all the 
resins used in varnish are of vegetable origin, and most of them 
from tropical or sub-tropical countries. They exude from trees 
where the bark is injured, and form lumps varying in size from 
very small pieces up to masses of many pounds weight. In a few 
cases resin which is collected from living trees is used; but for 
the most part the varnish resins are dug up from the ground, the 
trees having fallen and decayed, and the lumps of resin having 
become buried, sometimes as much as six feet below the surface. 
Having for many years been thus buried they have undergone 
change, become harder and better suited for use. After being 
dug up, cleaned, and sorted the resin is packed in boxes or bags, 
and in this condition market resins are bought at prices ranging 
from about 75 cents per pound for the choicest sorts to as little 
as 5 cents per pound for some inferior kinds. Probably a fair 
average price (1914) would be about 30 cents. The valuable 
qualities are clearness, hardness, high melting point, pale color, 
luster, and perfect solubility after melting in oil. As a rule these 
resins are not soluble in oil or in spirit of turpentine or benzene; 
but after melting they are found to be so changed that they 
dissolve in hot oil. 

MELTING RESINS. Most of them require a temperature 
of 550 to 650° F. to melt them properly, and in melting they lose 
10 to 25 per cent of their weight ; some species lose more and some 
less; the best and hardest resins lose about 25 per cent. If this 
is done in the laboratory with proper precautions it will be found 
that the temperature of the melted mass is much higher than 
that of the vapor, showing that chemical decomposition has 
occurred. All light-colored resins darken on melting, some more 



374 ELEMENTS OF INDUSTRIAL CHEMISTRY 

than others. The greater part of the distillate can be condensed 
to a liquid; this is not done in this country, but in England and 
Europe it is common, partly because by refining the liquid may 
be made use of as a turpentine substitute, and partly because it 
prevents the escape of gases which may be thought objectionable 
in residence sections of cities. 

COPAL. Copal is a popular or trivial name applied to varnish 
resins, about as indefinite in its meaning as the term " metal." 
It was originally a Central American native word, and was 
applied to any resin. It is now used only for varnish resins, 
but" does not designate any particular substance. In the varnish 
factory resins are commonly called " gums," although true gums, 
such as gum-arabic, are water-soluble. Colophony is always, 
and correctly, called rosin, and is never spoken of as a gum. 
Gum-varnishes mean oleo-resinous varnishes free from rosin. 

VARNISH NOMENCLATURE. One hundred pounds of resin 
is the conventional unit, and varnishes are described as containing 
so many gallons of oil to this 100 lbs. of resin, weighed before 
melting. Thus a 20-gal. Kauri, or 20 K., is a varnish made from 
100 lbs. Kauri resin, 20 gals, linseed oil, and (probably) 30 gals, 
spirit of turpentine, the amount of the latter not being mentioned. 
Ihe grade of resin may also be mentioned; thus, " 20 Brown 3 
half benzene " would be 100 lbs. Kauri of the grade known as 
No. 3 Brown Kauri, 20 gals, oil, 15 gals, spirit of turpentine 
(turps for short), and 15 gals, benzene. This is a fairly accurate 
description and any varnish -maker would recognize it. 100 lbs. 
of any resin counts for about 6 or 6 \ gals, in the batch; turps 
weighs 7.2 lbs. and benzene a little more than 6 lbs. per gal. 
So this would figure as follows : 

100 lbs. resin = 75 lbs. = 6 gals. 
20 gals, oil = 154 lbs. = 20 gals. 

15 gals, turps = 108 lbs. = 15 gals. 
15 gals, benzine = £0 lbs. = 15 gals. 



427 lbs. = 56 gals. 

Actually it will be more like 420 lbs. = 55 gals., because at 
least a gallon of the thinner will be lost by evaporation. 

LlNOXYN. When linseed oil is exposed to the air, either 
by blowing air through it or by exposure in thin films, it is changed 
into an elastic substance, not sticky or greasy to the touch, called 



VARNISH 375 

linoxyn. This is an oxidation product, and weighs considerably 
more than the original oil, probably about one -fifth more; dif- 
ferent experimenters have reached various results. Its specific 
gravity is higher than that of the oil, and it is apparent that the 
latter has contracted in volume as well as increased in weight. 
This product is insoluble in oil and in turpentine and most of the 
other oil-solvents, and is the elastic ingredient of oil-paints and 
oleo-resinous varnishes. When oil is spread out in a film and 
exposed to the air it does not for some time appear to change, 
but after a certain time it rather suddenly changes into a semi- 
solid, gelatinous, sticky condition. Up to this point being a liquid, 
any contraction which may have occurred causes no notable 
change; but now a somewhat solid film quickly forms, in which 
contraction produces a state of tension. It is obvious that if 
this film is at all inclined to be porous, contraction will open the 
pores, because it stretches the solid part of the film away from the 
openings; and this is probably the cause of the porosity of dry 
linoxyn films. 

POROSITY. If, therefore, we can add something to the oil 
which will act as a flux and postpone this preliminary setting 
until the compound, by absorbing more oxygen, is in a more stable 
condition, we shall decrease the final porosity of the film. This 
is probably what we do when we dissolve a resin in the oil. The 
resulting compound — varnish — does not take its initial set until 
it is more completely oxidized, and the film thus formed is more 
nearly free from pores than a pure linoxyn film. 

VARNISH FILMS. Such a film has two other advantages. 
First, it is harder and resists abrasion better, and it is smoother, 
which has the same effect; second, as the liquid varnish is more 
viscous than oil, it may be applied in a somewhat thicker layer, 
and a thick film is more lasting than a thinner one. The most 
obvious quality of a varnished surface is its smoothness and lus- 
trous appearance; its brilliancy depends not only on its smooth- 
ness but also on its high refractive power as regards light; those 
varnishes having the highest refractive indices being the most 
brilliant. This is increased, in general', by increasing the pro- 
portion of rosin. 

Outfit for Making Varnish. The varnish-maker's out- 
fit is very simple. A varnish kettle is a cylindrical copper vessel 
about 36 ins. in height and from 30 to 36 ins. in diameter, with 
a flat bottom. It has a loose cover, which is provided in the 
middle with an upright cylindrical outlet or " chimney " about 



376 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



5 ins. in diameter and 8 ins high; it has also a hole in it for a 
stirring-rod; and some styles have an opening for a large funnel. 
The kettle is loosely set on an iron truck or wagon with three or 
four wheels, so built that the bottom of the kettle, which rests 
on a ring only slightly less in diameter than itself, is not more 
than a couple of inches above the floor. There is a fireplace, 
consisting of a round pit sunk below the floor level lined with 
firebrick and having a grate, under which is an ash-pit and suit- 
able air-flue, and nearly over which, a little in the rear, is a spacious 
chimney, Fig. 110, which carries off the products of combustion 




Fig. 110. 



and also the vapor from the kettle. The fuel is coke, which burns 
freely and without much flame, which might set fire to the kettle 
vapor. The stirring-rod is of stiff steel, 5 or 6 ft. long, with a 
wooden handle. There is a large funnel, for use in pouring in 
oil, which may be put into the chimney in middle of the cover, 
or into a special opening in the cover near one side. 

VARNISH-MAKING. Into this kettle is put 100 or more, 
commonly 125 lbs. of resin, the kettle is placed on the wagon, 
and wheeled over the hot fire. As the resin melts the escaping 
gases cause foam, which makes it necessary that the kettle should 
be of considerable height and capacity. In about half an hour 
all the resin is melted ; some varnish-makers melt with the ther- 
mometer in the melting resin, others depend on feeling the dis- 



VABNISH 377 

appearance of lumps with the stirring-rod ; and from time to time 
the latter may be withdrawn and the adhering resin examined. 
Without removing the cover, the oil, which has previously been 
heated in another receptacle, is added ; some previously draw the 
kettle from the fire, others add the oil when the kettle is still on 
the fire. The oil and resin are cooked together, by the aid of the 
thermometer, until they are so combined that they will not sepa- 
rate on cooling; this is tried by putting a drop on a piece of glass 
or slate, and if it clouds on cooling the combination is not complete. 
In fact it is common to cook varnish more than this; the more 
it is cooked the greater becomes its viscosity, and the more 
turpentine it will take to thin it to the proper consistency. Vis- 
cosity is spoken of by American varnish-makers as "body"; 
an American says a varnish has a heavy body wUen an English- 
man says it is " stout/' 

THINNING. When sufficiently cooked, the oleo-resinous 
compound is, on the wagon, wheeled off to another room, well 
away from the fire, and a previously measured amount of spirit 
of turpentine (or benzene, or both) is slowly added with constant 
stirring. Varnishes are more or less colloidal solutions, and if 
some of these oleo-resinous compounds are thinned directly with 
benzene they form a swollen, gelatinous mass, insoluble in excess 
of solvent; while if a little turpentine is first added this makes 
a solution which may safely be diluted with benzene if desired. 
Some makers add driers directly with the turpentine to the hot 
varnish, others wait until it is cool. These driers are compounds 
of lead and manganese. 

Proportion of Ingredients. Nothing has yet been said 
about the quantity of oil to be added; in most varnishes it is 
the predominating ingredient. The larger the proportion of 
oil the more elastic and durable will be the varnish; the smaller 
the amount of oil, the harder, more lustrous and quicker drying 
it will be. 

Varnishes for furniture, which should be hard and brilliant, 
and free from the least tendency to tackiness, are made with 10 
to 15 gallons of oil to the hundred pounds of resin; those for 
interior house varnishing contain from 15 to 20 gallons of oil; 
and for outside work, exposed to the weather, 25 to 30 gallons. 
These 30-gallon varnishes require about 32 gals, of turpentine or 
other thinner; 10-gallon varnishes take about 25 gallons of thinner. 

RUBBING VARNISH. Rubbing varnishes contain 6 to 12 
gallons of oil; they are so called because they become hard 



378 ELEMENTS OF INDUSTEIAL CHEMISTRY 

enough in from 1 to 6 days so that the surface may be rubbed 
with powdered pumice-stone, sprinkled on a pad of felt wet with 
water, until all the irregularities of surface are ground away, 
thus forming a smooth (" level ") foundation for further coats of 
varnish. Those which contain even as much as 20 gallons of 
oil will in time become hard enough to rub; after which, by rub- 
bing with finer materials, they may finally be polished; but this 
beautiful finish is not as durable as the natural gloss, which is 
always left on work which is to be exposed to the weather. When 
one coat is applied over another it is always desirable to remove 
the -gloss by lightly rubbing the undercoat, as the following coat 
does not stick well and smoothly to a glossy surface. 

ROSIN. Common rosin, or colophony, is extensively used in 
making cheap varnishes. It is not a natural resin, but is produced 
in the distillation of crude turpentine, being the residue left in 
the retort after the spirit of turpentine is distilled off. It is an 
acid substance ; and before use it is made nearly neutral by com- 
bining with it about 5 or 6 per cent of lime (calcium oxide). This 
makes it harder, more brittle, less easily fusible. It is made into 
oleo-resinous varnishes very much as are the natural resins, but 
with much more drier added; these varnishes are softer and less 
durable than the former class, but are mixed with them to make 
mixed varnishes of low price and medium quality. For some 
purposes rosin varnishes are used alone. They have good working 
qualities, and a small admixture of a rosin varnish to a " gum " 
varnish is often advantageous. They are made at lower temper- 
atures than the " gum " varnishes, and the greater part of the 
tung or China wood-oil that is imported is used in rosin varnishes, 
on account of its superior drying qualities, in which it alone sur- 
passes linseed oil. 

PALE AND DARK VARNISHES. To make a pale varnish it 
is necessary to have pale resins, but in some cases the paler pieces 
are softer and less valuable. The dark grades of the better kinds of 
resin, such as Kauri, are of excellent quality, and for many — 
in fact, most — purposes moderately dark varnishes are just as 
good as any. Even the, dark varnishes (not black asphaltum) 
are transparent, and have an agreeable yellow or brownish-red 
color; on dark wood they have even a better effect than paler 
varnishes, to which they are in every other respect equal. 
There are, of course, some dark resins of inferior sorts; and 
some of the best pale resins, such as Zanzibar, are of unequaled 
quality. 



VARNISH 379 

BAKING JAPANS. As the hardening of varnish is due to 
oxidation, it follows that with an increase of temperature the 
process will go on more rapidly. It is equally true that the 
solvent will evaporate more quickly from spirit varnishes in a 
hot atmosphere, so that it is generally true of all varnishes. If 
the temperature is high enough to melt the resin of a spirit varnish, 
or to keep an oleo-resinous compound in a liquid state until 
oxidation is nearly completed, the resulting film will be non- 
porous. Varnishes designed for such use are called baking 
varnishes or baking japans; the best of them are the black 
japans, in which the resin is partly asphalt urn. These form 
coatings of great beauty and merit, strongly resisting both 
chemical and physical action. They are baked at varying tem- 
peratures; on wood, of course, at comparatively low heat, but 
on metal at as high as 400° F., though 300° F. is more common. 
The baking usually lasts three or four hours. The objects to be 
japanned are commonly dipped in the varnish and put directly 
in the oven. Since the drying is forced by the heat it is possible 
to use a varnish which would not dry at all (in any reasonable 
time) at ordinary temperatures, and such material is likely to be 
somewhat indifferent to chemical action. 

JAPAN DRIERS. Another class of japans, having no relation 
at all to the preceding, are composed of linoleates or resinates of 
lead or manganese, usually containing free oil, and often some 
resinous or oleoresinous varnish, and dissolved to a thin liquid 
with turpentine or more often benzene. These are also called 
driers, and they act by catalysis, inducing the rapid oxidation of 
the oil or varnish to which they are added. It is well known that 
lead and manganese form two classes of compounds — for example, 
a protoxide and a peroxide— and easily pass from one to the other. 
If they are present in the film in the higher state of oxidation they 
give up half their oxygen to the oil, then take up more from the air, 
and so act continuously as agents to pass along oxygen from the 
air to the oil. Manganese is more active than lead, but each has 
its advantages. Driers may be made with other metals, such 
as nickel and cobalt, which readily pass from one state of oxida- 
tion to the other, but have no special advantages over lead and 
manganese. These compounds may be made by direct heating 
of the metallic oxides with oil or rosin, or by decomposing soaps 
with soluble salts of these metals. If by use of these compounds 
we introduce into oil even as small an amount as two °f its weight 
of these metals, the effect is very marked. The use of too much 



380 ELEMENTS OF INDUSTRIAL CHEMISTRY 

drier is objectionable, since it is likely to continue to act, slowly 
of course, after the film has hardened, and in time destroy its 
elasticity and coherence. Driers are not used in spirit varnishes, 
nor usually in baking japans. 

BOILING OIL. Long-continued heating causes linseed oil 
to dry with a gloss, and oil which has been heated with a little 
lead and manganese oxides is called boiled oil; the untreated oil 
is called raw oil. Films of raw oil take 5 or 6 days to dry hard 
enough to be handled, while boiled oil will dry in 24 hours. For 
special purposes, however, oil is boiled for a longer time, and in 
this way is made the varnish used on patent leather and for some 
other uses. 

LITHOGRAPHIC OR " STAND " OIL. Linseed oil which has 
been bleached or otherwise refined so that it does not " break " 
is heated to a high temperature, usually 600° F., or higher, for a 
considerable time; it is then found to be viscid, like molasses; 
as it is heated without the addition of driers it is not what is called 
" boiled oil "; it is treated best in enameled kettles or aluminum 
or silver-plated copper kettles, so that it is not much discolored. 
This is in this country generally called lithographic oil, in Europe 
stand oil. It dries with a gloss, and is sometimes used for mak- 
ing enamel paints, being regarded as equal to a varnish. It is 
largely used in Europe in varnish-making, the melted resin being 
dissolved in it. Such a varnish requires less cooking than the more 
ordinary ones, and rather more turpentine or other thinner. 
They are pale in color; but American varnish-makers think 
they are less durable, the oil being too much changed, and not 
sufficiently combined with the resin. Stand oil is largely used 
in Europe in paint-making also. 

Driers are sometimes added to varnish after it is made. The 
varnish is warmed to 100 to 150° F. and agitated for several 
hours with powdered litharge and some powdered manganese 
compound, either borate or oxide. These lead and manganese 
compounds are dried immediately before use by heating them 
until it is certain that all the water is driven off. The amount 
used is considerable, 2 or 3 per cent, as that which is not absorbed 
will settle or can be filtered out, 



CHAPTER XX 
SUGAR 

INTRODUCTORY. Highly refined commercial sugar consists 
of sucrose. The word " sugar " as used in this article and com- 
mercial^ refers to sucrose of various degrees of purity. 

Sucrose is widely distributed in the vegetable kingdom; 
two plants, however, supply practically all of the world's sagar. 
These are the sugar-cane (Saccharum officinarum) and the sugar 
beet (Beta vulgaris) . Cane is grown throughout the tropics and 
in some sub-tropical regions; the beet is produced in most parts 
of Europe, the northern and Pacific Coast States of this country 
and in Canada. Very little sugar is produced in the British 
Islands, though excellent beets have been grown there experi- 
mentally. 

The stalks are cut close to the ground, freed of their leaves 
and the top joints are removed at the highest one showing signs 
of maturity. This point is determined by the color of the stalk. 
The clean stalks are removed to the factory as soon as possible 
after cutting. In Louisiana, however, owing to danger of frost 
damage late in the season, the stalks are cat and covered or 
windrowed and left in the fields until needed. This is not feasible 
in the tropics, as the cut cane would soon ferment if left in the 
fields, and must therefore be prompt ly milled. 

As the cane arrives from the fields, it is unloaded upon an 
elevator consisting of endless chains with projecting arms or upon 
a belt-like conveyor composed of endless chains and wooden slats. 
In several unloading devices, the loaded cane car is tilted end- 
wise or sidewise by hydraulic power and the load is discharged 
upon the elevator or conveyor. 

The conveyor delivers the cane into a preparatory machine 
called a shredder or crasher, according to its type, which tears 
it into shreds or crashes it. The mill rollers are so arranged that 
the cane is crushed twice by each 3-roll mill, and at each successive 
crashing the cane passes through a smaller opening than before. 
The last mill is usually " set " with its back or bagasse roll and 

381 



382 ELEMENTS OF INDUSTRIAL CHEMISTRY 

the top roll almost touching one another, or to use the factory 
term, " iron to iron." A curved knife or turn plate guides the 
crushed cane from one pair of rolls to the next. Notwithstanding 
the great strength of mill rolls and shafts these are often broken 
bj r the straining to which they are exposed. 

Water is usually applied to the crushed cane or bagasse, as it 
is now termed, as it emerges from the rolls of the first and second 
mills. The bagasse is in the condition of a sponge that has been 
squeezed nearly dry and quickly absorbs the water, which dilutes 
a part of the remaining juice. The subsequent milling of this 
moistened bagasse extracts more sugar than would be obtained 
with dry crushing. The water is often all applied to the bagasse 
from the next to the last mill and the thin juice from the last 
mill is pumped back upon the bagasse from the first. There 
are various modifications of this method, depending upon the 
number of mills in the series. In this method all the juice 
extracted by all except the last mill is pumped to the defecating 
apparatus for the next stage of the manufacture. This use of 
water on the bagasse is termed " saturation," " maceration " or 
" imbibition." 

The yield of juice by milling varies with the quality of the cane 
itself. Woody canes yield less juice than those of low fiber con- 
tent and immature canes more than ripe, rich stalks. By dry 
crushing, i.e., without saturation, 75 per cent on the weight of 
the cane of juice may be readily obtained with the immature 
canes of Louisiana, whereas in the tropics it usually requires very 
heavy milling and liberal use of saturation water to express an 
equivalent quantity. 

PURIFICATION OF THE JUICE. The juice as it flows from the 
mills is turbid and filled with impurities, both chemical and me- 
chanical. It is first strained through perforated brass sheets 
having 400 round holes and upward per square inch. The 
surface of the strainer is cleaned by mechanical scrapers, which 
deposit the fiber and trash upon one of the bagasse conveyors, 
to be again passed through a mill. 

DEFECATION PROCESS. The next stage of the purification 
is the defecation process. The raw juice is always of acid reac- 
tion. This acidity is neutralized with milk of lime, dry slaked 
lime, or powdered quicklime and the juice is then heated to coagu- 
late the albuminoids. 

In the ordinary method of defecation, the juice is first limed 
in mixing tanks to slight alkalinity or faint acidity, according to 



SUGAR 383 

the grade of sugar to be made, and is then conducted to defecators. 
These are tanks fitted with steam coils or steam jacket at the 
bottom. Many factories lime the juice in the defecator. The 
limed juice is now heated with steam. The heat is continued 
until a heavy blanket of scum rises to the surface and breaks or 
" cracks." When the cracking point is reached the heat is dis- 
continued and the juice is left at rest for the precipitates to settle. 
This process separates nearly all of the albuminoids, partly by 
coagulation, and a part of the acids, fat, wax and gums. Some 
lime salts are formed and persist throughout the manufacture. 
A part of these salts subsequently deposit upon the heating 
surfaces of the evaporating apparatus. If the process is conducted 
with care, there is no decomposition of the sugars, but with exces- 
sive liming the invert sugar is decomposed in part and forms 
dark, bitter compounds with the lime. These lime salts impede 
the crystallization of the sugar. The ripe cane frequently con- 
tains no levulose, but this sugar always appears in the molasses, 
even if no sucrose is inverted, and is attributed to the action of 
the salts upon the dextrose. In an acid defecation, as in making 
white sugar, if insufficient lime is used, inversion of sucrose occurs. 

After allowing sufficient time, usually an hour or longer, for 
the subsidence of the precipitates, the clear juice is decanted from 
between the blanket of scum and the mud at the bottom of the 
defecator. The clear juice is run into storage tanks preparatory 
to the evaporation. The scum and mud mixed together are 
pumped into filter presses and the filtrate is added to the clear 
juice already obtained. The press-cake is used as a fertilizer 
or on many estates is wasted. The sugar content of the cake is 
reduced by either washing it with water while still in the press 
or by removing the cake, beating it to a cream with water and re- 
filtering. The unwashed cake contains from 8 to 12 per cent of 
sugar, according to the richness of the cane and the quantity 
of water used in washing the mud from the defecators, and that 
by refiltration or thorough washing contains about 1 per cent. 

Phosphoric acid or acid phosphate of lime is often used in the 
defecation, especially in making white and high-grade yellow 
sugars, to form a voluminous precipitate, which carries down 
much flocculent and some coloring matter. 

EVAPORATION. The purified juice is next evaporated to a 
sirup of about 54° Brix (30° Baume). The evaporation is con- 
ducted in multiple-effect vacuum evaporators. There are several 
types of these multiple-effect evaporators, but the basic prin- 



384 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



ciple of all is the same. The evaporation is so conducted that 
a stream of juice is fed into the first vessel and flows from effect 
to effect, gaining in density as it travels, and finally finished 
sirup of the desired density is constantly pumped from the 
third effect. This method may be extended to four vessels, 
which is termed a " quadruple-effect,'' and so on. Owing to 
mechanical difficulties, this so-called standard type of evaporator 




Fig. 111. 



is not used with more than four vessels. The water from the steam 
condensed in the calandrias is used for boiler feedwater and the 
surplus for maceration , of bagasse and other purposes, thus 
utilizing its heat. 

Crystallization of the Sugar. The concentrated juice 
or sirup is pumped from the multiple effect to storage tanks 
preparatory to the crystallization of the sugar. The crystalliza- 
tion is accomplished in a single-effect vacuum pan such as is 
shown in Fig. 111. 



SUGAK 385 

The vacuum or strike pan, Fig. Ill, is a cylindrical vessel, A, 
usually of cast iron, having a dome-shaped top with vapor pipe, B, 
and a conical bottom provided with a strike or discharge valve, C. 
The pan is equipped with large heating coils of copper, and steam 
and vacuum gauges, also sight glasses, D, for watching the prog- 
ress of the work, a proofs tick for drawing test samples and suit- 
able pipe connections for sirup and molasses. The steam enters 
a manifold, E, from which it is distributed to the coils; each of 
the latter has a stop valve for steam, and drainage connections 
for condensation water. The vapors from the boiling sugar solu- 
tion pass through a save-all, F, connected at the bottom with the 
pan, where they expand and meet baffle plates, so that sugar 
entrained with the vapor may be returned to the apparatus. 
The vapors from the evaporating liquor pass into a condenser, G, 
in which they meet a shower of water. The incondensable gases 
are led off through a pipe, K, from the lower part of the condenser 
to a vacuum pump. The condensing water and water of con- 
densation are carried off through the " leg pipe " or torricellian 
tube, H. The foot of the leg pipe is sealed with water in the hot 
well, /. 

The above is a description of the " dry vacuum system." It 
is so called because only the incondensible gases are separately 
removed by the pump. In the " wet system " the condensing 
and condensation waters and the gases are carried off by the 
vacuum pump. The dry system is preferred for large instal- 
lations. Many factories use a condenser in common for the 
multiple effects and vacuum pans. 

In crystallizing the sugar, the pan boiler proceeds as follows: 
Having produced a vacuum in the pan he draws in what he deems 
to be sufficient sirup for gaining the " strike," and evaporates 
it to a saturated sugar solution at the desired temperature. He 
regulates the boiling-point by the injection of water into the 
condenser, thus controlling the vacuum. When ready to form the 
crystals, i.e., grain the strike, he heats the liquor to a tempera- 
ture of from 60 to 70° C, the grade of sugar desired determining 
this condition. 

After the formation of the crystals the pan-man continues 
the boiling, injecting sirup by charges or continuously if he so 
elect, to compensate for the water evaporated and obtain a satu- 
rated solution, but always avoiding temperature and other con- 
ditions favorable to further formation of crystals. The charges 
must be large enough to enable the crystals to circulate freely 



3S6 ELEMENTS OF INDUSTRIAL CHEMISTRY 

but not too large in proportion to the crystal surface. This forces 
the sugar to deposit upon the crystals already present, which 
soon grew to the desired size. The material is now concentrated 
to a solid content of about 92 per cent more or less, and is termed 
" massecuite." The steam is shut off, air is admitted to the pan, 
and the " strike " is discharged through the foot-valve into suit- 
able recipients. 

In making small-grained sugar, the crystals are formed when 
the pan is about half filled with concentrated syrup. " Low 
graining " produces a coarse sugar. If very large crystals are 
desired, a part of the strike is removed from the pan or is " cut- 
over " through pipes into an adjoining pan, and the boiling is 
resumed. If the cut-over pipe is used both pans may be filled 
with large-grained sugar or one strike may continue with sirup 
and the other be completed with molasses to form a lower grade 
massecuite. 

PURGING AND CURING THE SUGAR. The massecuite, after 
the completion of the crystallization, is conveyed to mixers, from 
which it is drawn off into centrifugal machines for the separa- 
tion of the molasses from the crystals. 

The centrifugal consists of a shallow drum or basket, having 
perforated walls and lined with finely perforated brass sheets or 
brass wire cloth. A customary size for large machines is 40 ins. 
diameter by 24 ins. depth. By suitable transmission a machine 
of this size is rotated about 1000 revolutions per minute. A charge 
of massecuite is run into the centrifugal, usually while the latter 
is slowly revolving and the speed is then increased until the 
molasses is thrown off by the centrifugal force and the sugar is 
retained by the perforated lining. 

In making raw sugar for refining, after the above treatment, 
the crystals are ready for packing and shipment. In the event, 
however, of the crystals not testing sufficiently near the market 
basis, 95 per cent or 96 per cent by the polariscope, according 
to market conditions, after all but the closely adhering molasses 
has been thrown off by the centrifugal, a little water is sprayed 
upon the wall of sugar, which quickly removes a part of the low- 
test molasses from it. Sugars polarizing approximately 96° are 
termed " centrifugals " and are the basis of market quotations 
for raw sugar. 

In making white sugar in the factory, the juice having 
been purified as has been described, the crystals are thoroughly 
washed in the centrifugal with water. Usually a little ultra- 



SUGAB 387 

marine is added to the water " to kill " the yellow tinge of the 
crystals. 

Beet Sugar 

Raw Material and Its Preparation. The sugar beet is 
grown from seed. The rows are seeded thickly and the young 
plants are thinned to leave vigorous ones about 6 ins. apart in 
the rovv. The desirable beet is small, the topped root weighing 
about a pound, and is tapering, somewhat top-shaped, regular 
in form and has few rootlets. Large beets are not usually as rich 
as the small ones described. 

In preparing the beets for the factory, they are topped at the 
lowest leaf scar and are then hauled to the factory, where they 
are stored in sheds or in the open upon platforms, according to 
climatic conditions. When necessary to pile the beets in the field 
for any length of time, they are protected by a light covering of 
leaves and earth. Climatic conditions determine the methods 
of storage. In very cold, even climates in the United States 
very large piles of beets have been successfully stored on open 
platforms. The frost affects only the outer layers, and as the 
thawing is gradual the beets are but little damaged. 

The beets are flushed to the factory in flumes, waste water 
being used largely for this purpose. They are elevated to the 
washing machines by an apparatus which also removes many of 
the adhering stones and are thoroughly cleansed. From the wash- 
ing machines they are elevated to automatic scales, above the 
slicers, for weighing. 

EXTRACTION OF THE JUICE. The juice is extracted by the 
diffusion process. The washed and weighed roots are conveyed 
to the slicing machines, which cut them into more or less V-shaped 
slices or cossettes. The slices are packed loosely in the cells of 
the diffusion battery, which extracts the juice by a somewhat 
imperfect process of dialysis, the cell walls supplying the mem- 
brane. 

The diffusion battery consists of a number of cylindrical iron 
vessels, usually twelve, with suitable pipe connections, heating 
devices and top and bottom doors. The pipes are so arranged 
that the liquid may be conducted from one vessel to the next, 
entering at the top or bottom, at the will of the operator, and 
permitting any vessel to be disconnected from the series for 
charging with slices and discharging the spent pulp. A general 



388 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



view of the upper part of a circular diffusion battery is shown 
in Fig. 112. 

In operating the battery, a vessel or diffuser is filled with beet 
slices, then warm water is turned into it at the bottom connection, 
driving out the air through a cock in the cover; by the time this 
diffuser is filled with water, the next one has been charged with 




Fig. 112. 



beet slices; the direction of the current of liquid in the first is 
reversed, the water now entering at the top, and the thin juice, 
as it now is, passes into the second diffuser at the bottom, expel- 
ling the air as from the previous vessel. The thin juice is heated 
in transit and passes into successive diffusers as they are filled with 
slices. When about ten or eleven vessels have been filled, 
according to the number in the battery, a measured volume of 
juice is drawn from the last one filled, the water pressure applied 
at the first diffuser of the series forcing the juice to circulate. 



SUGAR 389 

Air pressure is used in many factories, when drawing a charge 
of juice, to promote economy of water and sugar. The use of 
water is sometimes preferable, as with it the exhausted pulp 
may be flushed through canals to the elevators. The spent 
pulp is elevated to continuous presses in which a large part of 
its water is expressed. The juice drawn as described is strained 
through depulpers and conducted to tanks for the next stage 
of the manufacture. 

The slices in the first diffuser of the series are now practically 
exhausted, but 0.15 per cent sucrose, more or less, remaining in 
them. This vessel is disconnected from the series and the 
exhausted pulp or cossettes discharged from it. 

From now on each time a vessel is charged with beet slices 
and juice, a measured volume of juice is drawn from it and the 
spent pulp is removed from the first diffuser of the series, each 
diffuser in regular order containing the exhausted pulp. The 
rate of filling the diffusers depends upon their shape, size, the 
number in the battery and the capacity of the factory. The 
usual rate of filling is a diffuser of beets every six to seven 
minutes. 

PURIFICATION OF THE JUICE. The beet juice always con- 
tains very fine pulp that passes the strainers of the diffusion 
battery. This pulp is largely removed by special strainers called 
" depulpers," and a part of it is carried down with the carbonate 
of lime in the purification of the juice. 

The liming is followed by the double or even triple carbona- 
tion process. Both the liming and carbonation are usually 
spoken of as the " carbonation process." 

Carbonic acid is forced into the limed juice through distribu- 
ting pipes. The lime is precipitated as a carbonate and salts 
of the acids of the juice. The carbonate carries down mechan- 
ically many of the impurities that have separated and also much 
of the coloring matter. The injection of carbonic acid is con- 
tinued until the juice retains an alkalinity equivalent to about 
1 to 1.5 grams of calcium oxide per liter, using phenolphthalein 
as an indicator. Should this carbonation be carried too far, 
many of the impurities would again pass into solution. The 
juice foams considerably during this operation, and steam jets 
oil or grease are often used to beat it down. Very deep tanks 
are used in modern installations to obviate the use of steam, 
grease, etc. The use of steam is objectionable on account of its 
decomposing action on the sucrose in the foam. 



390 ELEMENTS OF INDUSTRIAL CHEMISTRY 

At the conclusion of this carbonation the juice is heated to 
near its boiling point and is then filter-pressed. The filtrate 
flows into the second carbonation tanks. The juice usually still 
contains sufficient lime, but in some factories a small quantity, 
about 0.25 per cent, is added. It is again carbonated, this time 
at a temperature near 100° C. This is termed the " saturation." 
The injection of carbonic acid is continued until only slight 
alkalinity due to lime remains. In determining the end point 
the alkalinity due to other alkalies than lime must be taken into 
account. The usual alkalinity of the saturated juice due to lime 
is 0.01 per cent or slightly higher. 

Evaporation, Crystallization, Purging and Curing 
THE SUGAR. These processes and the apparatus used are 
practically the same as those employed in the cane-sugar industry 
already described. 

The American factories usually produce granulated sugar. 
The granulator is simply a dryer so arranged that the crystals of 
sugar are separated from one another during the progress of the 
drying. 

The granulator is a long sheet-iron cylinder, placed in a nearly 
horizontal position and arranged so that it can be revolved. Nar- 
row deflecting plates or shelves are attached to the inside walls 
of the cylinder and extend throughout its length. The apparatus 
is inclined slightly toward the discharge end, at which are attached 
wire screens for sifting the sugar; there is also at this end a 
small room, one wall of which is formed of steam coils. A steam 
drum extends from end to end of the dryer at its axis. At the 
inlet end of the apparatus there is a suction fan to draw air through 
it and a hopper for feeding in the moist sugar. There are several 
types of dryers, but all depend upon the same principles. 

As the sugar leaves the centrifugal machine it is elevated 
to a mixing floor. It is here thoroughly mixed, since all the pans 
of sugar and all the centrifugal charges are not of uniform color. 

The sugar is next fed into the granular or dryer, through which 
a current of hot air is drawn by the suction fan. The crystals are 
carried upward by the revolving cylinder and in falling from the 
shelves, through the heated air, are separated and dried. By 
reason of the inclination of the dryer the sugar travels to the dis- 
charge end, where it is classified by the sieves and delivered to 
the packing spouts. 



SUGAR 391 



Sugar Refining 



RAW MATERIAL. Most cane-sugar factories make raw sugar 
testing from 95° to 98° by the polariscope and known commercially 
as 96° " centrifugal sugar." The Cuban product usually polarizes 
approximately 96° and that of Java and the Hawaiian Islands 
up to 98°. Many factories make a lower grade of sugar, a soft 
sugar crystallized at rest in tanks and testing about 87° and often 
lower. The market basis for these sugars is 96° and 89° respec- 
tively. There is an addition to the price for tests above and a 
deduction for those below these numbers. The increment of price 
per degree above these numbers is smaller than the deduction for 
those below. Similarly the price paid for the sucrose in an 89° 
sugar is less than that for the sucrose in a 96° sugar. These mar- 
ket conditions discourage the production of sugars much below 
96° Of the sugars imported into New York probably over 80 per 
cent test above 94°. 

Mingling, Washing and Defecating. The raw sugar 
is carried by elevators to mingling machines, which mix it with 
sirup and form a magma. This permits spinning the sugar in 
a centrifugal precisely as though it were a massecuite and thor- 
oughly washing the crystals. This station is termed the " wash 
plant." The washed sugar is melted with water to form a liquor 
of about 60° Brix, and a coefficient of purity of about 98.5° to 
99°. The washings or sirup are used in part in mingling raw 
sugar for subsequent magmas and the remainder is pumped to 
the defecators or " blow-ups." The blow-ups are provided with 
perforated pipes through which steam is blown into the liquors. 

Sufficient milk of lime is added in the blow-up to render the 
solutions strongly alkaline and then the alkalinity is neutralized 
with monocalcic phosphate solution or phosphoric acid. The 
reagents are used in sufficient quantity to produce a large precip- 
itate that separates sharply from the solution. After the addition 
of the reagents the liquor is heated in the blow-up to a temperature 
of approximately 82° C. 

BAG FILTRATION. The warm liquor obtained as above is 
run into bag or Taylor niters. These filters consist of a large 
number of heavy twilled cotton cloth bags about six feet long. 
These bags are attached to nozzles or " bottles " and suspended in 
a cast-iron chamber. A cotton sleeve of smaller diameter is 
placed over each bag. This causes the bag so to arrange itself 
as to give the effect of a fluted filter. 



392 ELEMENTS OF INDUSTRIAL CHEMISTRY 

The flocculent precipitate from the defecation, consisting of 
tricalcic phosphate, organic lime salts, gums, etc., and carbon 
from the bone-black dust, are retained in the bags and a brilliant 
filtrate flows from them. 

The precipitate or " mud " is first washed with hot water 
while it is still in the bags partly to free it of sugar. After this 
preliminary washing the bags are taken from the chamber, the 
mud is removed and they are given a thorough and systematic 
washing in a series of tubs. The bags are passed through a wringer 
on their way from tub to tub. The mud and " mud water " 
are filter-pressed and the filtrate is evaporated with other " sweet 
water " to a sirup in a multiple effect evaporator. The " thin 
wash-water " from the bag filters and the washings from the raw 
sugar packages are evaporated with the press filtrate. 

CHAR FILTRATION. Animal charcoal, bone-black or " char " 
filters are cylindrical iron cisterns about 10 feet in diameter and 
20 feet deep. These are filled with bone charcoal. 

High-grade bag-filtered sugar liquor, heated to about 71° C, 
is passed over the char and is followed successively and syste- 
matically by granulated sirup, i.e., the run-off sirup obtained in 
purging sugar to form the " granulated " grade, washings and other 
low-grade solutions. In making " soft white " sugars, the liquors 
are filtered in succession through three filters of char. The 
liquors flowing from the char are separated into grades according 
to their color and test. These grades are considered in the 
vacuum-pan work. 

When the char no longer decolorizes the solutions properly, 
the sugar is washed from it with hot water and is largely recovered. 
When the purity coefficient of the washings falls too low to 
admit of profitable treatment for the recovery of the sugar, the 
water is run to waste. The rich washings are concentrated with 
other sweet water. 

The wet char is discharged from the filters and is dried with 
the heat of the kilns that would otherwise be wasted. The dried 
char is heated or " burned "at a dull red heat in tubular retorts 
in kilns with exclusion of ( air from the retort. This process is 
termed " revivification." The organic impurities of the sugars 
that have been absorbed during the filtration are burned 
and the char is returned to filter service in practically as good 
condition as before use. The char may be used over and over 
again a great many times, a revivification following each use. 
The dust is removed by screening and must be compensated for by 



SUGAR 393 

the addition of from 25 to 50 per cent of new bone-black annually. 
About 50 to 60 hours are required for a complete cycle of filter 
operations. 

The filtration of sugar solutions through animal charcoal is 
primarily for the purpose of removing their color. The char has 
the further property of absorbing much of the non-sugar of the 
raw material and thus promotes the crystallization of the sugar. 
A good char will absorb 85 per cent of the coloring matter, 33 per 
cent of the inorganic matter and 50 per cent of the organic non- 
sucrose contained in the raw sugar solution filtered through it. 

It may be seen from these descriptions that the char filter 
station is one that requires skill and a thorough control in its 
conduct. Errors of judgment here may result in an inferior 
product and a loss of sugar. 

Crystallization and Curing the Sugar. Before con- 
sidering this stage of the refining a few definitions are necessary : 
Refiners term a solution from which no sugar has been removed 
a " liquor," and one from which sugar has been extracted a 
" sirup." The " sirup " of the raw sugar factory corresponds to 
the liquor of the refinery and the "molasses" of the factory to 
the sirup of the refinery. 

The crystallization of the sugar is accomplished in vacuum 
pans in general as described in the raw-sugar section of this 
chapter. The liquors have a very high initial purity as com- 
pared with the factory sirup, and, therefore, require repeated 
crystallization sufficiently to impoverish the final or barrel sirup. 
The crystals are formed at a high temperature in boiling hard 
sugars such as granulated, usually above 77° C. This tempera- 
ture is maintained long enough to produce sharp, clean crystals. 
In boiling soft sugars, on the contrary, a low pan temperature 
and very white liquors are essential. A comparatively dark- 
colored liquor will yield white sugar if the crystallization is con- 
ducted at a high temperature, since the crystals will be hard and 
absorb little coloring matter from the sirup. 

The methods of pan boiling as above described are typical 
of a refinery making only hard white sugars. Where soft white 
and yellow sugars are to be made, the aim is to produce a product 
of low polarisation and good color by combining suitable liquors 
and sirups and usually boiling the pans at low temperatures. 

The sugars are purged of sirup in centrifugal machines. The 
subsequent stages of manufacture depend upon the grade of sugar 
that is required. Granulated sugar is cured as has been described 



394 ELEMENTS OF INDUSTRIAL CHEMISTRY 

for beet sugar, by drying and separating the crystals in a granu- 
lator or dryer. Cube sugar is made by molding the moist sugar 
under pressure and then drying it in an oven. The yellow and 
soft white sugars are packed while moist, as they leave the cen- 
trifugals. Powdered sugar is obtained by grinding very coarse 
granulated sugar and bolting it through silk bolting cloth. Loaf 
sugar and tablets are cut or broken from loaves and slabs molded 
from a magma of white sugar and high-grade white liquor. 

There is a very large number of grades of refined sugar, the 
classification depending upon color, grain, etc. 



CHAPTER XXI 
STARCH, GLUCOSE, DEXTRIN AND GLUTEN 

Starch and Starch Granules. Starch is widely dis- 
tributed in the tissues of the higher plants, and makes up the larger 
part of the solids of grains and tubers. AY hen pure, it is a fine 
white powder having a density of 1.6 and at ordinary temperature 
is quite insoluble in water, alcohol, ether, or other common sol- 
vents. Under the microscope, starch appears as minute, white, 
translucent grains varying much in size and shape, but so charac- 
teristic that it is usually comparatively easy to determine their 
botanic origin. 

If starch is heated to about 70° C, the exact point varying 
somewhat according to its nature and origin, it pastes or swells 
up into a pasty jelly, the viscosity of which also varies much in 
different starches. The microscope shows this to be due to the 
granulose swelling through absorption of water, and bursting the 
granule. The granules can be gradually ruptured mechanically 
by grinding starch with sharp sand or in similar ways, or the 
" cellulose " can be removed by chemical reagents such as dilute 
solution of caustic alkalies or zinc chloride, when pasting occurs 
readily in cold water. 

CLASSIFICATION. Commercial starches are classified accord- 
ing to their pasting characteristics into thick- and thin-boiling. 
The old-fashioned laundry wheat-starch is typical of the first class 
as a 5 per cent water mixture pastes into a thin translucent sirup, 
scarcely gelatinous at boiling temperature. Corn starch, such 
as sold for food, when mixed with boiling water in the above pro- 
portion, forms a practically non-fluid paste and is characteristic 
of a il hick-boiling starch. It is now known that these variations 
in pasting properties of starch of different kinds are largely 
dependent on the conditions of manufacture and that thick- 
boiling starches can be made thin-boiling by suitable treatment. 

These properties as well as the degree of gelatinization of the 
cold paste are of great importance in preparing starches for cer- 
tain trades. In laundry work and the textile manufactures, for 

395 



396 ELEMENTS OF INDUSTRIAL CHEMISTRY 

instance, the demand for a paste thin enough to penetrate the 
fabric when hot without coating the surface and at the same time 
with body enough to give the requisite stiffness make certain 
types of thin-boiling starches highly desirable. Thin-boiling 
starches are also used extensively in confectionery. In other 
industries, as in paper-box making and in certain lines of textile 
work, thick-boiling starches are required. 

SOURCES. Notwithstanding the great variety and wide 
distribution, there are comparatively few sources of commercial 
starch. By far the greatest amount manufactured in the United 
States is made from Indian corn (maize), which averages about 
55 per cent starch and of which about 40,000,000 bushels are 
consumed annually in the manufacture of commercial starches 
and derived products. Considerable potato starch is also made 
in this country as well as some wheat starch, the latter being 
prepared from flour. Tapioca and sago starches are imported 
to some extent from the far East, the latter used particularly 
in the manufacture of envelope gums. Cassava starch from 
Florida and the West Indies has a limited use, and is noted for 
the body of its paste. 

Method of Manufacture. The general principles of 
starch manufacture are: (1) Disintegrating the plant tissue in 
such a way that the starch grains are set free but not ruptured ; 
(2) separating the gluten by diluting with water the disinte- 
grated mixture which has previously been treated with chemicals, 
or subjected to fermentation, and then settling out the heavy 
starch by subsidence; (3) washing the starch by agitating 
with water in tanks, " running " or decantation; (4) recovery 
of the starch by draining in cloth-bottom draining boxes or in 
deep frame filter-presses; (5) drying the starch in kilns. 

The corn is shoveled from the railroad cars into conveyors, 
from which it is spouted into the steep tubs, which are large 
wooden vats containing about 2000 bushels. Here it is soaked 
from two to four days in warm water containing about 0.2 per 
cent of sulphurous acid. The water is circulated through the 
corn and by means of an adjoining heating tank is kept at a 
temperature of 50° C. (120° F.). The sulphurous acid seems 
to have a softening effect on the glutinous parts of the kernel 
and at the same time prevents undesirable fermentative changes. 
When the grain is thoroughly softened by the steeping so that 
the contents of the kernel can be readily disintegrated by moder- 
ate pressure, it is usually passed through a Fuss mill. This mill 



STARCH, GLUCOSE, DEXTRIN AND GLUTEN 397 

in its essentials consists of two parallel vertical plates, rapidly 
revolving in opposite directions and carrying studs which project 
between each other. The corn dropping between these plates 
is thoroughly, although not finely broken up. The tough, rubbery 
germ at the apex of the kernel, which contains practically all of 
the oil, over 30 per cent of its weight, passes out entire, and is 
separated from the rest of the grain by passing the mass, mixed 
with an appropriate amount of water, through germ-separators, 
which are tanks containing agitators so constructed that the 
movement brings the germs to the surface, where they are removed 
by an appropriately placed spout and sieves, the heavier parts 
of the grain passing off below. The germs are drained and 
washed from adhering starchy liquor, dried, ground and the oil 
pressed out of the warm mass by means of oil-presses of the 
usual construction. This oil is used principally for soap making 
and for the manufacture of a vulcanized product and in rubber 
making, although it can be applied to most purposes to which 
a semi-drying oil can be put. The remaining oil cake is an excel- 
lent cattle food. It is ground into meal or shipped in the original 
cake, the latter, owing to its compactness and unalterability, 
being particularly adapted for export. The remaining disin- 
tegrated grain is mixed with water (liquor from the separators), 
reground in a buhr-stone mill, and the semi-liquid mass passed 
over the shakers. The shakers are inclined bolting-cloth sieves 
of about 200 mesh. The starch granules with most of the gluten 
are washed through the bolting-cloth by jets of water or starch 
liquor, while the woody portions fall off the lower end of the sieve. 
This process is usually repeated two or three times, the bran 
after each shaking being passed through roller mills such as are 
used for grinding flour. The bran or " wet feed " is finally 
passed through the slop machine, which wrings out the enclosed 
liquor and is either sold for cattle feed in this moist state or it 
may be dried, being often mixed with the gluten meal. 

The starch and gluten liquor from the shakers is agitated in 
tanks to keep the starch in suspension, and its density adjusted 
to 4-6° Be. It is then passed over the runs or tables, which are 
practically level, the incline being usually only about 4 ins. for 
troughs 120 ft. long and 2 ft. wide. As the liquid slowly 
flows down the run, the heavy starch granules, rolling over each 
other, are practically freed from the adherent coagulated part 
of the gluten and are deposited upon the bottom, the gluten 
being carried off the end of the trough. Men with wooden pad- 



398 ELEMENTS OF INDUSTRIAL CHEMISTRY 

dies keep the surface of the deposited starch smooth to prevent 
loss of the starch through any cutting action that might be caused 
by irregular depositing or accidental obstruction. 

The deposited starch, which extends in a layer of about 1 ft. 
thick at the upper end of the run to practically nothing at the 
foot of the run, is shoveled out of the troughs into cars running 
on a track over the top of the trough and is then dumped into the 
breakers. The breakers are tanks provided with revolving 
agitators, by means of which the starch may be mixed to a thick 
cream with water and washed once or twice by decantation accord- 
ing to the quality desired, or it may be purified by revolving 
again on the tables. 

The gluten liquors from the tables always contain consider- 
able starch which cannot be recovered as commercial starch. 
The liquors, therefore, are settled to remove the excess of water 
and the residue passed through filter-presses, the 'cake thus 
formed being dried, ground, and sold as gluten meal. 

This gluten meal is often mixed with corn bran to form gluten 
feed. The starch milk is either lun into molding boxes, wooden 
frames with cloth bottoms, to drain off the water, or filter-presses 
with deep frames are used. 

DRYING METHODS. The starch is either dried in trays 
forming pearl starch, or boxed, packed tightly in paper-lined boxes, 
and then the partially dried cake transferred to the drying kiln. 
The kilns are of various designs. Some are in the form of wooden 
tunnels, through which the cars containing the starch are pushed 
along by the cars of wet starch entering at one end, the cars of 
dry starch being taken out at the other. The temperature 
varies considerably at different parts of the kiln and depends on 
local factory practice, 160-180° F. being the customary tempera- 
ture for pearl starch, the drying taking eighteen or twenty hours. 
Lump starch which is boxed is allowed to dry partially at a much 
lower heat, the blocks turned out of the frames being placed 
on shelves in a kiln the temperature of which is about 130° F. 
A yellowish crust which is about \ in. thick forms on the out- 
side of the blocks; this is removed and the mass of clean, white 
starch again returned to the kiln, where it is dried for several 
days at a temperature of about 160° F. During this drying the 
lumps split up into miniature basaltic-like masses, technically 
known as crystals. The size of the crystals can be regulated by 
the temperature; a low heat giving larger and more irregular 
lumps. 



STARCH, GLUCOSE, DEXTRIN AND GLUTEN ■ 399 

Starch when air dried contains from 12 to 15 per cent of mois- 
ture, and if more thoroughly dried in the kilns it will soon absorb 
water when exposed to the air until the above percentage is 
reached. The moisture in starch varies also with the humidity 
of the air; starch dried by heat being one of the most hygroscopic 
substances known. 

ALKALINE STARCHES. The description given above applies 
specifically to the manufacture of the so-called neutral, thick- 
boiling starches, and in general to corn starch. In making 
alkali starches, caustic soda is added to the starch and gluten 
liquors before running so as to make the gluten more soluble. 
Such starches have less nitrogenous impurities but are high in 
ash, as it is impossible to wash all of the alkali out. Alkaline 
starches give thicker pastes than neutral starches made by the 
sweet or sulphite processes. 

THIN-BOILING STARCHES. Thin-boiling starches are made 
by subjecting the starch to a treatment with very dilute acids 
at temperatures below the bursting point of the granule, usually 
35-50° C. This causes an incipient hydrolysis of the contents 
of the granule, but does not perceptibly affect the enveloping 
starch cellulose, the dried product being indistinguishable from the 
original starch, even by careful microscopic examination. A 
certain very small amount of the granule contents is rendered 
soluble and can be removed by washing the starch with cold 
water and filtering. The amount and nature of this soluble 
carbohydrate, which can be detected by adding a drop or two 
of a very dilute iodine solution, depends on the extent of the acid 
modification. 

Two general methods of making thin-boiling starches are 
used in factory practice. The first, known as the drying in proc- 
ess, consists in adding either sulphuric or hydrochloric acid in 
very dilute form, usually about 1 per cent upon the weight of 
the crude green or mill starch as taken from the runs mixed with 
water. The excess of liquid is then drained off and the starch 
allowed to dry gradually at a gentle heat. This process has been 
practically suoerseded by the in suspension process, in which case 
the green starch is dumped into a tank of hot water containing 
0.1-0.2 per cent of acid and kept in suspension by means of 
agitators. When the process is complete, as shown by pasting 
tests, the acid is neutralized, the starch is drained and then dried 
in the usual manner. — This latter process has been developed 
largely by Duryea, who has taken out patents. These thin- 



400 ELEMENTS OF INDUSTRIAL CHEMISTRY 

boiling starches are now made in large quan cities, having largely 
taken the place of wheat starch in the laundry trade. 

POTATO STARCH. Practically all of the starch used in Europe 
is made from potatoes. Potatoes contain only from 17 to 20 
per cent of starch, but the actual yield per acre is more than either 
corn or wheat, for the reason that the potato yield is 6| tons 
per acre against about 25 bushels for corn and 31 for wheat, or 
less than a ton of grain. 

The potatoes are soaked in vats of water for several hours 
and then washed in a long trough containing a spiral stirrer which 
tosses them about, thus giving a thorough rubbing. Some fac- 
tories use revolving cylinders for the same purpose. The potatoes 
are then introduced into rasping machines equipped with rapidly 
evolving knives, the pulp thus formed being passed through 
sieves to remove the fiber and the filtrate allowed to settle. The 
lower layers of white starch are drawn off and the upper gray 
layers still containing some fiber are received and settled, this 
being repeated several times. The starch is then purified on 
runs and dried in a similar manner to corn starch. 

Potato starch is often made thin -boiling by methods analogous 
to those used in corn-starch modifications. Certain patented 
processes designed to purify the starch by oxidizing the nitrog- 
enous compounds by use of potassium permanganate and other 
oxidizers also produce thin-boiling modification. Commercial 
potato starch usually contains about 20 per cent of water. 

WHEAT STARCH. Wheat starch is usually made from flour, 
either by the old-fashioned method of allowing the mixture of 
flour and water to ferment in vats and then purifying the starch 
by settling, in which case the gluten is destroyed by fermentation 
and a thin-boiling starch results, or by the Martin process, in which 
the gluten is saved and a thick-boiling starch produced. In this 
latter process, masses of dough made by moistening the flour 
are placed in a special kneading machine in which the dough is 
kneaded by grooved rollers working in a swinging frame, the 
starch being washed out through sieves by jets of water, settled 
and passed over runs. The resulting starch when dried and 
finished is thick-boiling and the gluten, still containing several 
per cent of starch which it is impossible to remove mechanically, 
is recovered as a rubbery mass. 

COMMERCIAL GLUCOSE AND OTHER PRODUCTS OF STARCH 
HYDROLYSIS. Starch, according to Brown and Morris, is a 
highly condensed hexose carbohydrate of the formula {C^lioO^n, 



STARCH, GLUCOSE, DEXTRIN AND GLUTEN 401 

consisting of approximately 100 anhydride groups which can be 
resolved by suitable hydrolytic agents into as many equivalents 
of dextrose, providing the hydrolysis is sufficiently prolonged. 
Dilute acids will produce complete hydrolysis, the rate depending 
on the nature of the acid and varying approximately as the con- 
centration, but increasing rapidly with rise of temperature. When 
starch paste is subjected to the action of an acid, it is gradually 
resolved into simpler carbohydrates, the reaction being the result 
of the breaking up of the numerous anhydride groups of the com- 
plicated starch molecule with the formation of hydroxyl radicles 
from the water present, the acid not going into the combination 
but acting catalytically. 

The speed at which this hydrolysis proceeds depends on the 
amount and nature of the acid and the temperature. If the 
hydrolysis is carried to completion, the final product is a glucose 
sugar called dextrose, although in actual practice some small 
quantity of decomposition products are usually formed. The 
intermediate hydrolytic substances are very complicated, but 
behave chemically and physically as molecular aggregates of 
three bodies — dextrose, a biose sugar known as maltose, and a 
dextrin with the properties of the original starch paste. 

This progress of the hydrolysis, or conversion of starch paste, 
manifests itself by characteristic chemical and physical changes. 
The thick paste loses its colloidal nature and rapidly becomes 
more limpid, the concentration of the solution increases, although 
the dissolved carbohydrates become specifically lighter, and the 
solution becomes distinctly sweeter in taste. If tested with a 
weak aqueous solution of iodine, the deep sapphire blue given by 
the original starch paste changes as the hydrolysis proceeds, 
passing into violet, then to a rose red, which in turn changes to 
a reddish brown, which grows steadily lighter until just before 
complete hydrolysis is reached it disappears altogether. A few 
drops of the solution poured into strong alcohol give a copious 
white precipitate during the early stages of the conversion; as 
the hydrolysis continues the amount of precipitate becomes less 
until near the end, when no precipitate is produced. 

If the conversion products are tested polariscopically, it 
will be found that there will be a progressive fall in specific 
rotation values from that of starch paste (202°) to that of 
dextrose (52.7°). The Fehling test shows no copper reduction 
with starch paste, at the beginning of the hydrolysis, but pro- 
gressively increases till the maximum reducing power is reached, 



402 ELEMENTS OF INDUSTRIAL CHEMISTRY 

when all of the converted products are finally transformed into 
dextrose. 

Since the discovery of the process of converting starch into 
dextrose by the action of heat and acids, as long ago as the begin- 
ning of the last century, dextrose in a crude form and known as 
starch sugar or grape-sugar has entered more or less into commerce, 
but its importance as a product is small as compared to that of 
glucose, which latter has been developed in the past thirty years 
and become practically indispensable in many food products. 

The term " glucose " as used to define this product must not 
be confounded with dextrose or its isomers, but has reference to 
a special commercial sirup, which is always sold under this desig- 
nation. The name " corn sirup," which has been suggested, 
would seem to be a happier designation, as is the German " Starke- 
zucker sirop." It is a thick, viscid sirup, practically clear and 
colorless, or of light amber tint, and is a product of the partial 
hydrolysis of starch. Its composition varies somewhat, but the 
average product has a specific rotation of about 140°, with a 
Fehling reducing value of about 47 per cent that of dextrose. 

MANUFACTURE OF GLUCOSE. Glucose is manufactured on 
a large scale in this country conjointly with starch, gums, dextrins, 
and numerous valuable by-products. Practically all of the com- 
mercial product is made from corn (maize), what is known as 
" No. 4 " being usually taken, although all grades are used. The 
following diagram outlines the process and will assist in following 
the steps, which as far as the production of the green (crude) 
starch are identical with those of corn starch manufacture which 
has already been described. 

The green starch is taken directly from the tables to the con- 
verter, being shoveled off the runs, and mixed with water in a 
breaker, a tank with an agitator, to a thick cream, usually standing 
about 20° Be. 

The converted liquor is turbid from the colloidal albumi- 
noids it contains and has a density of about 16° Be. It is imme- 
diately blown out of the converter into the neutralizer, which is 
usually a large covered wooden tank provided with a stirrer and 
also having ventilating shafts for the removal of hot vapors. 
Here it is treated with a dilute solution of sodium carbonate, 
which not only neutralizes the acid, but at the same time coagu- 
lates the colloidal albuminoids and precipitates the dissolved iron, 
so that a bright filtrate is obtained. 

From the neutralizer, the liquor goes to bag-filters of the 



STAECH, GLUCOSE, DEXTEIN AND GLUTEN 403 

Scheme of Glucose Manufacture 
Corn 

i 

Steep Tubsv 

^Steep-liquor 
Germ Separators— Fuss Mills \ 

Evaporators 
Oil Presses Buhrstone Mills / 

/i i / 

/ (Oil) Rolls / 

/ \ 1 / 

(Germ-meal) Shakers— Wet-Feed (bran) Slop-machine 

Starch tables 
| ("runs") 



\ 

Filter presses (" Green " Starch) 
Dryers Breakers 

/ i 

Mills Converter 

/ i 

(Gluten-meal) Neutralizer 

Evaporator 



Bag Filters (Bag liquor) 

Bone-char filters 

(Light liquor) 
Evaporator 

(Heavy Licuor) 
Bone-char niters 

i 

Vacuum pan 

I 
Finished Glucose 



404 ELEMENTS OF INDUSTRIAL CHEMISTRY 

type used in sugar refining (Taylor filters). The practically 
clear amber-colored bag-liquor usually goes thence to the bone- 
char filters for its first decolorization, but often it is first sub- 
jected to a further treatment with precipitants and filter-pressed 
before going to the bone-char. 

The glucose is passed twice through the bone-char filters, the 
first passage follows bag-filtering, resulting in what is known as 
light liquor. This liquor is evaporated in a multiple-effect appara- 
tus to a density of about 30° Be., and again goes to the bone- 
char filters, when the product is known as heavy liquor. 

The practically colorless heavy liquor coming from the bone- 
char filters is now ready for the final boiling down in the vacuum- 
pans, whence it comes as finished glucose and is run into the 
barrels for shipment. 

Glucose as used for the manufacture of table sirups is usually 
known as mixing glucose. Such sirups are made from cane 
sirups, usually refinery molasses, or from white sugar and glucose 
in the proportion of 85 per cent of glucose to 15 per cent of cane 
sirup. Table salt and sometimes small quantities of vanillin 
are often added. The other principal uses of glucose are in the 
manufacture of jellies, preserves and in brewing, although its 
applications are multifarious in many industries where it does 
not enter as a food product, as for instance, it is used in enormous 
quantities to fill sole leather and tanning extracts. 

DEXTRIN AND BRITISH GUM. Artificial gum made from 
starch and known as dextrins and British gums are made in large 
quantities both in this country and Europe, and are employed 
in many ways as substitutes for natural gums, such as tragacanth 
or gum arabic. Enormous quantities of these starch gums are 
used in the textile industries, for envelopes and postage stamps. 
These products are made by heating (roasting) starch in revolving 
cylinders, which are heated directly by a furnace or by an oil- 
bath, or in shallow trays in shelf kilns. The temperatures used 
vary much according to the product desired, varying from 170 
to 270° C. In making dextrins, lower temperatures are used 
and the starch is moistened with dilute acid, usually nitric, 0.12 
per cent previously to heating, so that in the earlier stages of 
heating considerable hydrolysis takes place. In making British 
gums usually no acid is used, but the temperature employed is 
higher, and even in this process hydrolysis first takes place to 
some extent, owing to the moisture and acid naturally in the 
starch. The time of heating varies much according to the prod- 



STARCH, GLUCOSE, DEXTRIN AND GLUTEN 405 

uct, white dextrins taking but two hours, while British gums 
are heated for fifteen hours or even longer. There are no exact 
standards for dextrins generally recognized, color and body of 
the mucilages which measured quantities of these gums make 
are usually the best means of their valuation. These products 
are not definite chemical compounds, neither are they made 
according to fixed methods of procedure. Often different prod- 
ucts are blended to give the properties desired. Little is known 
of the chemical constitution of these products, however much has 
been assumed. They contain some products of acid hydrolysis, 
it is true, but they are not in the main identical with products 
of acid hydrolysis. 

GLUTEN. The protein matter known as " gluten, " which 
forms the largest proportion of the organic material associated 
with starch, is necessarily removed or destroyed in the process 
of starch manufacture. By the more modern processes the 
gluten is saved and formerly these semi-liquid gluten deposits 
were sold to the neighboring farmers for immediate feeding to 
their cattle. Now, in the manufacture of corn starch the gluten 
which is settled out of the liquor coming from the starch runs 
is filtered in filter-presses, and the cake dried and pulverized, 
making a valuable cattle food, especially when mixed with the 
corn bran or similar material. 



CHAPTER XXII 
BEER, WINE AND LIQUOR 

BREWING is the process of preparing hopped, fermented 
beverages, such as lager beer, ale, stout, weiss beer, the materials 
usually employed being barley-malt, hops, and water. 

MALTING. This is the process of preparing cereals, usually 
barley, for brewing purposes. 

Barley is the favorite cereal employed, chiefly because the 
husk acts as an excellent filtering material in the mash-tun; 
its endosperm is readily modified and mellowed during growth, 
unlike corn; and it develops a sufficiency of enzymes during the 
malting process. 

MALTING OPERATIONS. Broadly these embrace every ma- 
nipulation from the moment the crude grain leaves the elevator 
or storehouse up to the time the finished malt is conveyed to the 
storage bin or to the hopper to be measured into the crusher mill 
of the brewery. In a more confined sense, as treated here, the 
term is applied only to the three main operations of steeping, 
germination and kiln-drying. 

Growth. Germination as conducted on a smooth floor, con- 
structed of cement for this purpose, is the traditional method, 
the process being called " flooring," " growing," or " germinat- 
ing." The modern methods, however, are based on artificial or 
forced aeration (pneumatic malting) either on a perforated floor 
or in revolving drums. Another important distinction is, that 
by the old method the work s almost entirely done by hand, 
whereas the improved methods may with much propriety be 
called mechanical malting, most of the work being done by 
machinery. 

Floor Malting. The barley from the bins is loaded on the 
conveyor and carried automatically to the cleaning machine. 
The offal goes to feed dealers. 

Steeping. From the cleaning machine the barley drops into 
the separator underneath. The different grades, two or three 

406 



BEER, WINE AND LIQUOR 407 

in number, go to the automatic scales, and then reach the steep- 
ing tank, which should be half filled with water. At first, the 
water should stand 1 to 2 ft. above the barley when the tank is 
full. The skimmings are floated off or skimmed off with a ladle. 
They go to a separate bin or trough, and are dried and sold for 
feed. Change the water twice the first day and once a day 
thereafter. Steep for about forty-eight hours, modifying for 
dryness of air, hardness and temperature of water, type and 
condition of barley, etc. 

Germinating. The grain being fully steeped, the water is 
drained off at the bottom and the barley dropped on the malting 
floor; otherwise it is loaded on trucks and wheeled to the floor, 
where the grain is spread and leveled to a heap or " couch " of 
about 8 to 10 ins. Here it is turned from time to time by hand 
shovels and its height gradually increased and again reduced 
according 1 to conditions from about 14 ins. to 4 or 5 ins. The 
temperatures in the air should be about 50 to 60° F., in the 
growing malt couch about 75°, turning to prevent too high heats 
and to supply aeration. Growth takes about five days for barley 
of the Manchuria type and eight days for Bay Brewing and two- 
rowed types, like the Chevalier. When the endosperm has 
become mellow and acrospire is three-quarters up, the " green 
malt " is conveyed to the kiln, which usually has two or three 
floors heated by open fire assisted by closed heaters; hard coal, 
being smokeless, is commonly used for fuel. 

Kilning. By a fan installed above the upper floor air is sucked 
through the malt together with the products of coal combustion. 
The temperature is kepc at about 90° F. on the upper floor, and 
when hand dry, usually after twenty-four hours, the malt is 
dumped on the lower floor, where it is kept for about twelve hours 
at 120-130° F., where it is kept until practically dry, when it is 
heated to the final temperature of 150-155° F., for pale beers, 
165-180° for darker beer, and up to 220° F. for beers of Munich 
character. 

BREWING MATERIALS. The materials commonly employed 
wherever beer is produced are hops, malt and water. In some 
countries, like England, sugars and other adjuncts are used in 
part with malt; in the United States corn is commonly employed 
besides rice and sugars. In Germany the employment of any sub- 
stitutes for or adjuncts to malt is prohibited. Barley is the dis- 
tinctive cereal that furnishes malt, the exception being wheat 
used for weiss-beer malt. 



408 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Malt and Cereals. Malt is produced from barley by the proc- 
esses of cleaning, steeping in water, germinating on the floor 
or in compartments or drums, kiln drying. 

Properties of Matt. The berries should be of uniform size 
and shape; husk and endosperm of light color for pale beers; 
it should be free from other grain like wheat or oats, or seeds 
like mustard, rape; odor aromatic, not musty; growth uniform 
with about 90 per cent of acrospire three-quarters up; condition 
of endosperm mellow, not flinty; laboratory yield on dry basis 
about 72 to 74; moisture content not over 6 per cent, lest slack 
ness ensue; strong diastatic and peptic power for proper inver 
sion of starch and albumen; bushel weight not less than 34 nor 
more than 38 lbs. 

Corn is employed, with germ and husk more or less removed, 
in the form of grits or meal in a separate cooker or in the form of 
flakes in the mash-tun; rice, either broken or as meal, in the 
cooker; wheat in flaked condition in the mash-tun or crushed 
(by means of malt mill) in cooker. 

Malt yields about 64 to 70 per cent of extract in the brewery, 
of which 4 to 5 per cent are albuminoids; rice about 75 to 80 per 
cent; corn about 75 to 78 per cent; wheat about 65 to 70 per 
cent, of which 2 to 3 is albumen; rice and corn yield practically 
no albumen. 

The employment of unmalted cereals like rice and corn 
offers a number of advantages. They can generally be obtained 
at a lower price and yield more extract than malt. They lend 
themselves better to the production of beers of Bohemian or Vienna 
types than all malt, because American malt generally yields more 
albumen to wort and beer than European malts, due to higher 
albumen content of American barley of Manchuria type. Amer- 
ican all-malt beers are therefore apt to be more satiating than 
Bohemian beers with their lower albumen content. The result- 
ant beers are of paler color, of greater stability when pasteurized, 
and their brilliancy less affected by low temperatures. 

The employment of wheat may not be more economical, 
nor are the wheat beers more stable or less sensitive to low tem- 
peratures than all-malt beers. They have a peculiar palatable- 
ness that recommends them in some localities. 

Commercial glucose and other brewing sugars are prepared 
from the starch of corn through inversion by acids at high heats 
(under pressure). They contain dextrose and dextrin in vary- 
ing quantities. 



BEER, WINE AND LIQUOR 409 

Other Adjuncts. Dark malts. For preparing a beer of dark 
color a malt may be used which has been subjected to special 
treatment in the kiln, so as to acquire a dark color, such as 
caramel malt, the husk of which is yellowish brown, wnile the 
endosperm has a decidedly brown color. In its preparation, 
ordinary malt of good quality is steeped for a while, so as to take 
up a certain amount of moisture. It is then dried, and heated 
in suitable vessels, first to a comparatively low temperature, 
in order to promote the formation of sugar, and later to higher 
temperatures, at which the sugar is caramelized. Black malt 
is dried at higher temperatures, so that both the husk and the 
endosperm possess a blackish-brown color. It does not have the 
pleasant caramel taste of caramel malt. The coloring power 
is very great. Malt color is an extract of black malt, filtered and 
evaporated to a sirupy consistency. Roasted corn is prepared 
from corn in the same manner as black malt from barley, i.e., 
by heating to higher temperatures. Its coloring power equals 
that of black malt. 

Hops. Hops as they are used in the brewery are cone-shaped 
formations, representing clusters of blossoms of the female hop 
plant. From forty to sixty flowers are grouped together on a 
central spindle, which is zig-zag shaped, forming a so-called hop 
cone or the umbel of the hop. 

At the time of maturity the seed of the hops and the whole 
lower and inner parts of the bracts are covered with a fine light- 
yellow dust, consisting of minute granules of lupulin, which con- 
tain both the bitter and aromatic principles of the hops, viz., 
the hop oils and resins, besides hop tannin, hop bitter acids, hop 
wax, nitrogenous bodies, carbohydrates and mineral substances, 
an enzyme (diastase) which is of special importance in ale brew- 
ing. 

Mashing. Mashing is the process of extracting the good 
by mixing them with water at suitable temperatures and in 
proper relative quantities, preparatory to boiling in the kettle. 

Chemically it proceeds in the main by the inversion of the 
starch into maltose, malto-dextrin, and dextrin, and the modi- 
fication of the insoluble albuminoids into a soluble form. These 
changes are brought about by the agency of two substances 
which are contained in the malt, and begin operations when the 
malt is mixed with water at definite temperatures. 

These substances are called diastase and peptase. They were 
formerly called chemical ferments, as distinguished from the 



410 ELEMENTS OF INDUSTRIAL CHEMISTRY 

organic ferments, which are responsible for fermentation. At 
the present day the term enzymes, or soluble ferments, is more 
commonly applied to them. It is the function of the diastase to 
invert the starch, of the peptase to modify the albuminoids 
of malt as above indicated. 

The amounts, both absolute and relative, of dextrin, malto- 
dextrin and maltose, as well as of the modified albuminoids like 
albumoses, peptones and amides, finally present in the wort, are 
materially affected by the conditions under which the enzymes 
do their work. Hence, it is in the power of the brewer to control 
the, composition of the wort, within certain limits, by modifying 
such conditions. 

Boiling the Wort. The wort obtained by mashing is boiled 
for a certain period for the purpose of eliminating or rendering 
harmless certain undesirable constituents, Hke coagulable albu- 
minoids, and introducing other new bodies, like hop resin and hop 
oil, by extraction from the hops. Besides, during heating and 
boiling the wort assumes a darker shade, due to carmelization 
of the sugars; water evaporates, resulting in a denser liquid, 
and the tannic acid of the hops coagulates an additional quantity 
of undesirable albumen, this coagulation aiding in clarifying the 
wort and causing it to " break." 

The wort should not be allowed to rest longer than fifteen 
minutes, as a dark color or rank, bitter taste may result if wort 
is left in contact with hops too long. The hop-jack is pro- 
vided with a false bottom, through which the wort is drained into 
a pump that delivers it to the coolers. The hops remaining on the 
false bottom are sparged with hot water to wash out the wort 
they contain. If the wort remains in hop-jack very long, or if 
the spent hops are pressed out to obtain the wort, a rank bitter 
taste of the beer is apt to result. 

Cooling. The wort reaches the surface cooler, a large, shallow 
iron pan, and remains here a short period for the purpose of 
preliminary cooling. The wort should be cooled to 145° F., 
and not lower, on the surface cooler, and receive proper aeration 
during cooling, avoiding all sources of contamination in the 
meantime. Aeration of the wort during cooling has the effect 
of further precipitating undesirable albuminoids. Besides, the 
wort absorbs air, which is utilized by the yeast later on. 

Pitching with yeast. Fermentation is induced in the wort 
by adding yeast properly prepared, which operation is termed 
" pitching." The common practice is to mix the yeast with an 



BEER, WINE AND LIQUOR 411 

equal quantity of finished wort or boiled first wort of about 
55-60° F., rouse well to insure aeration and breaking up of cell 
aggregations, transfer to settling tank when the mass is in fer- 
mentation, mixing with it the wort as the latter runs from the 
cooler. 

Fermentation Phenomena. Within fifteen or twenty-four 
hours, according to the pitching temperature, little white bubbles 
appear around the sides of the vessel. The beer at this time is 
covered with a dark head of a thick consistency, composed largely 
of albuminoid matter, coagulated during the boiling period 
(sludge). The head of impurities being skimmed off, the whole 
surface is found to become quickly covered with a fine white 
froth (" whitening over "), rather higher around the rim than in 
the middle, denoting that carbonic acid gas is escaping through 
the fermentation of the sugar (maltose) . 

Kraeusen. The head of froth begins to move from the sides 
of the vessel to the middle, and assume a frizzled appearance, 
small cockle-shaped mounds beginning to rise all over the surface. 
At the expiration of twenty to thirty-six hours after pitching, the 
surface should be early and pure white ("young kraeusen"). 
From the time the froth head begins to move toward the middle, 
fermentation becomes more active, the head rising all the time 
("high kraeusen"). At the same time the temperature rises, 
slowly at first, more rapidly as the activity of fermentation in- 
creases, while the saccharometer indication or density decreases 
more rapidly, the drop amounting to one-fourth to one-half 
of one per cent a day in the early part, and reaching one to one 
and one-half toward the high kraeusen stage. The curly head 
of froth turns a darker color while rising in height. 

The high kraeusen stage is reached seventy to eighty hours 
after pitching and is maintained for a period of forty-eight to 
seventy-two hours, varying according to different influences. 
During this time the fermenting beer is kept at a certain low 
temperature, 48 to 50° F., and as high as 58° F., by means of 
attemperators, and when the head begins to collapse is cooled 
slowly to 39° F. The saccharometer falls more slowly as the end 
of the principal fermentation draws near. When the end is 
reached, the fall of the saccharometer is commonly fa to -fa per 
cent in cwenty-four hours. 

The yeast, which had been kept in suspension during fer- 
mentation through the escape of carbonic acid gas, should now 
be found settled on the bottom of the fermenter: the amount 



412 ELEMENTS OF INDUSTRIAL CHEMISTRY 

being about three to four times the quantity used for pitch- 
ing. 

Tanking the Beer. The beer is brought from the fermenting 
vat to the stock tank either at the temperature to which it has 
been cooled in the ferment er, and then it undergoes a secondary 
fermentation, or it is further chilled on its way to the stock 
cellar, passing it through a cooler, in which case no secondary 
fermentation is anticipated and the beer should reach the stock 
tank thoroughly fermented. 

Storage is that stage in which the beer is kept after the con- 
clusion of the primary fermentation and prior to final clarifica- 
tion for the trade package. 

The objects of resting the beer are to eliminate certain sus- 
pended matter, like yeast, thereby securing greater clearness, 
and certain objectionable matters, like albumins, thereby securing 
greater durability, especially in pasteurized bottled goods. 

During the storage period there should be a slight progiess 
of secondary or after-fermentation, unless final attenuation was 
reached previously. The residue of maltose and part of the 
maltodextrin are fermented by slow degrees, the amounts of 
carbonic acid and alcohol increasing. 

The yeast settles the more quickly the less sugar there is 
present and the smaller the storage vats; the albumins are the 
more thoroughly eliminated the better the mash was peptonized, 
the lower the storage temperature, and the longer the period of 
storage. Hence, long storage at low temperatures enhances the 
stability of beer after pasteurization. 

Starch particles do not settle on storage. Nor can dependence 
be placed on improving the beer through long storage in respect 
to number of bacteria it contains. On the contrary, bacteria 
may increase during storage. 

Low temperatures while the beer is in storage are necessary 
to precipitate the albumins and to check the development of 
bacteria. The storage cellar should be kept as near to the 
freezing point as possible. 

When sufficiently matured in storage, the beer is run or 
pumped into chip casks, so called from a method of clarifying 
beer by means of chips. 

Treatment in the chip cellar has a twofold object: 

1. To impart to the beer the necessary life, that is, a suffi- 
cient amount of carbonic acid gas, so that it will foam properly 
when tapped. This is done: 



BEER, WINE AND LIQUOR 413 

a. by kraeusening and bunging, or 

b. by charging with carbonic acid gas directly (carbonating) , 

or 

c. by both kraeusening and carbonating. 

2. To make the beer brilliant. This is done: 

a. by the addition of chips; 

b. by the addition of isinglass ; 

c. by filtration. 

Kraeusening. This consists in the addition of kraeusen beer> 
that is, young beer in the first, or kraeusen stage of fermentation, 
twenty-four to forty-four hours after pitching, the amount being 
about 15 per cent for home draught beer, 10 per cent for export 
draught or bottle beer, or 5 per cent when beer is carbonated. A 
few days after the kraeusen have been added the finings are intro- 
duced and the cask is bunged, to prevent the escape of the gas 
generated by the kraeusen, its accumulation causing a pressure 
which is termed bunging "pressure and which is allowed to rise to 
about 5 lbs. 

Carbonating. Carbonic acid fermentation gas may be intro- 
duced into the beer at any stage after fermentation, but usually 
this is done while the beer is being transferred from the chip cask 
to the racking bench and before it reaches the filter. When beers 
are carbonated they are either not kraeusened at all or only with 
relatively small quantities of kraeusen — about 5 or 6 per cent. 
The gas is introduced either on the pressure principle by spraying 
the beer through a compressed atmosphere of gas or on the 
aspirator or injector principle, by forcing the gas into the beer, 
usually in a conduit while in motion. 

Clarification. Matter remaining in suspension at the end of 
the storage period is eliminated by mechanical means. First 
among them is the introduction of chips. Beer chips or clarifying 
chips are strips of wood, usually of beech or maple, so cut as to 
present a maximum of surface with a minimum of volume and 
weight. The chips are spread in the bottom of the chip cask, 
where they retain particles in suspension, reaching them as well 
as the sedimentation caused by the employment of isinglass. 
Chips must be carefully prepared by boiling in water, with an 
addition of soda. 

Fining the Beer. Brewers' finings are prepared from so-called 
isinglass, obtained either from fish through cleaning, rolling and 
drying the bladder, or from hide of calf. The finings may be pre- 



414 ELEMENTS OF INDUSTRIAL CHEMISTRY 

pared on the cold or warm plan, their efficiency depending upon 
the amount of gelatinous substance the isinglass yields and which 
in flocculent form distributes through the beer, enveloping the 
suspended particles and carrying them to the bottom. One 
pound of isinglass is sufficient for one hundred to five hundred 
barrels of beer. 

Filtration. The process of filtering beer consists in forcing 
the beer on its way from the chip cask to racking apparatus, 
generally by means of air pressure applied at the chip cask, or 
through a pressure regulator pump interpolated between chip 
cask and filter, through one or more layers of compressed fibrous 
material, called filter mass, which commonly consists of cotton 
fiber. Beer should always pass through the filter under back 
pressure, as it will otherwise foam to such an extent as to pre- 
clude the proper filling of the trade packages. It should stand in 
a cold place, if practicable, in the chip cellar. 

Back -pressure Racking. The principle of back-pressure rack- 
ing is to create in the delivery package a back pressure suffi- 
ciently high to prevent foaming of the beer, so as to permit of 
readily filling the package without loss of time and without the 
foaming and loss of beer accompanying the practice of " gut rack- 
ing " which formerly obtained. 

WINE. The Grapes. The quality of a wine depends mainly 
upon the quality of the grapes from which it is made, and the 
latter is determined by a number of factors, such as variety of 
grapes, treatment of the vines, soil and its cultivation, climatic 
conditions and the degree of ripeness which the grapes are allowed 
to reach. 

It is only where a suitable variety of grape is grown under 
especially favorable conditions as to soil and climate that the high- 
grade wines can be produced. Under other conditions the iden- 
tical grape variety may give a wine of a distinctly different 
character. The Riesling grape, when growm in California, is 
different from the Riesling that finds ideal conditions for its devel- 
opment in the temperate climate of the sunny hills along the 
Rhine, and the name Riesling on the label of a California wine 
therefore invites a comparison that cannot but result in adverse 
criticism. The wine growers of each territory, when selecting 
and developing those varieties of grapes that are best suited to 
local conditions, and modifying their methods accordingly, may 
gradually develop wine types of their own to be judged entirely 
upon their own merits. 



BEER, WINE AND LIQUOR 415 

It is important that the grapes be picked at the proper time, 
which usually means when fully ripe. If picked at an earlier 
stage they give a must containing less sugar but richer in acids. 
For this reason early picking is sometimes resorted to in southern 
countries, where the hot and dry climate tends to produce little 
acid and much sugar. Over-ripeness of the grapes is undesirable, 
as it will cause them to shrink and their skin to burst, laying open 
the juice to the dissolving action of rain and dew and offering 
breeding places to dangerous " disease " germs. 

The weather during the picking is not without importance. 
Rain will, to some extent, dilute the must; heat will accelerate, 
while cold will retard the subsequent fermentation. 

Stemming, Crushing and Pressing. After being gathered and 
carted to the winery, the grapes are to be prepared for the fer- 
mentation as quickly as possible. Any delay is likely to detract 
from the quality of the resulting wine. If the production of white 
wine is intended, the grapes, which may be either red or colorless, 
are crushed and pressed, only the juice (must) being fermented; 
if red wine is to be produced red grapes are stemmed and crushed, 
the whole pulp being filled into fermenting vats, where the color- 
ing matter is extracted during fermentation. In some cases the 
stems are left in the fermenting pulp, but as a rule they are removed 
either before or after the crushing. 

The device used for stemming may consist in its simplest 
form of a wire-screen, with meshes of a size to permit the grapes 
but not the stems to go through, over which the grapes are 
pushed by hand with a rake. Another device, intended for 
machine power, consists of a horizontal perforated cylinder in 
which a shaft with helically arranged arms revolves, thereby 
carrying the stems toward one end and causing the grapes to fall 
through the perforations. 

The machine in wmich the grapes are crushed usually consists 
of a hopper feeding the grapes to a pair of adjustable grooved 
rollers revolving in opposite directions and with unequal speed. 
The purpose is thoroughly to open up all of the grapes without 
crushing the seeds, from which undesirable substances would 
otherwise be extracted, whence the rollers are adjusted accord- 
ingly. Part of the must is often allowed to drain off from the 
crushed grapes by gravity alone and may be fermented sepa- 
rately and is superior to the rest of the must that is obtained 
by pressing. 

The winepresses are mostly ordinary screw-presses; sometimes, 



416 ELEMENTS OF INDUSTKIAL CHEMISTEY 

however, hydraulic presses are used. The crushed grapes are 
spread in a uniform layer over the press-bed and subjected to a 
gradually increasing pressure. Too strong pressure should not 
be applied at once, lest the yield be diminished. As already 
stated the pressing of white wines takes place before, that of 
red wines after, fermentation. 

The Must. The grape juice is a watery solution, the main 
constituents of which are: 

1. Sugar; 4. Flavoring substances; 

2. Organic acids; 5. Pectine and mucilaginous substances; 

3. Albuminoids; 6. Mineral substances. 

1. The sugar during fermentation is split up into about 
equal parts of alcohol and carbonic acid, and only very little sugar 
(less than 0.15 per cent) should be left in ordinary dry wines. A 
must containing 16 to 17 per cent sugar will produce a table wine 
with an alcoholic strength of 8 to 8.5 per cent by weight; musts 
containing less sugar produce the light, ordinary wines; those 
containing more sugar result in the heavier high-grade wines. 

2. The organic acids, tartaric and malic, although present in 
comparatively small quantities, are very essential constituents 
of the must. The tartaric acid mainly occurs in combination 
with potassium as tartrate (bitartrate of potassium), which is pre- 
cipitated to a large extent during the fermentation. A part of 
the acids is also consumed by the yeast and by certain bacteria, 
which accounts for the fact that a wine has less acidity than the 
corresponding must. The total acidity of must or wine is usually 
given as the apparent percentage of free tartaric acid. 

To make a wine palatable its acidity must be in proper ratio 
to its alcoholic strength and palatableness. A light wine without 
prominent flavor and body may appear fully harmonious as to 
taste with an acidity of only 0.4 per cent, but a heavier, highly 
flavored, wine would taste quite flat when possessed of this same 
acidity and may require as much as 1.0 per cent acidity to appear 
harmonious. 

A must usually loses from 0.2 to 0.6 per cent in acidity during 
its transformation into wine. 

3. The must can contain up to about 1 per cent of albuminoids, 
of which only approximately one-half remains in the wine, the 
rest being partly utilized as nourishment by the yeast, and partlv 
precipitated during the fermentation. 



BEER, WINE AND LIQUOR 417 

4. The flavoring substances of the must, upon which its quality 
largely depends, are present in too small quantity to be determi- 
nable by chemical analysis, and we possess at the present time 
only scant knowledge of their chemical nature. 

These flavoring substances increase during fermentation, the 
fermented must containing: (1) Those originally present in the 
must ; (2) others formed during the fermentation, probably mainly 
by decomposition of certain albuminoids (amino-acids) contained 
in the must, and (3) the specific flavoring substances produced 
by the different varieties of yeast irrespective of composition of 
the must. 

5. The pectine and mucilaginous substances causing the thick 
consistency of the must are practically all precipitated during 
the fermentation, as they are insoluble in dilute alcohol. 

6. In a normal must is found from 0.3 to 0.5 per cent of 
mineral substances (ash), the amount of w T hich considerably 
decreases during the fermentation owdng to the precipitation of 
potassium in the form of tartar. 

The wine maker tests his must to determine approximately 
the sugar and acidity of an average sample. The sugar is deter- 
mined by means of areometers, such as Oechsle's must scale, indi- 
cating how many grains one liter of must weighs more than one 
liter of water, or Balling's saccharometer, indicating the per- 
centage of solids in solution. Degrees Oechsle divided by 5, or 
per cent Balling multiplied by f gives the sugar content in per 
cent of an ordinary must with sufficient accuracy for practical 
purposes. The acidity is measured by titration with standard- 
ized alkaline solutions. Knowing the ratio of sugar to acidity 
the wine maker is in a position to carry out the subsequent opera- 
tions with a view 7 to either checking or facilitating the decrease 
in acidity according to the requirements. 

A direct correction as to composition may also be found 
desirable. If lacking in acidity the must can be corrected by the 
admixture of less ripe grapes or by the addition of tartaric acid. 
The addition of gypsum, which is sometimes used, especially in 
making red w r ines, has a similar effect, the gypsum reacting upon 
the tartar so as to form insoluble calcium tartrate and bisulphate 
of potassium, which latter substance, unlike the tartar, remains 
dissolved in the wine. This method, the so-called plastering, 
can only be used to a limited extent, since the laws of most wine- 
producing countries fix a maximum limit for sulphates contained 
in unadulterated wine. 



418 ELEMENTS OF INDUSTRIAL CHEMISTRY 

If the must is too rich in acids, the acidity can be reduced by 
dilution with water and the proper sugar content eventually 
restored by addition of pure cane or grape sugar. This process, 
known as gallizing, is used to some extent in northern countries, 
especially for white wines, and is generally considered legitimate, 
provided it is carried out so as actually to improve, or to render 
marketable, the product and not with a view unduly to increase 
its quantity. 

The Fermentation. When left to itself the must will soon begin 
fermenting. It grows quite turbid, gas bubbles rise to the sur- 
face, the temperature rises and the viscosity and specific gravity 
decrease. At the same time the sweet taste gradually changes 
into a vinous one and a distinct flavor develops. Toward the 
end of the fermentation the turbidity gradually disappears and 
the completed fermentation leaves the young wine in a limpid 
state on top of a heavy sediment. 

These changes are brought about by certain microscopical 
plants that are always present on the skins of ripe grapes. Among 
them the yeasts which cause the alcoholic fermentation, splitting 
up sugar into alcohol and carbolic acid, are desirable and indis- 
pensable, while others, such as mycoderma and various bacteria, 
are undesirable disease germs. 

Between the microorganisms a struggle for life goes on in the 
must, each one striving to utilize the nourishment on hand for its 
own growth and producing substances that are injurious to its 
competitors. By far the most important task of the wine maker 
is to assist the yeast in this struggle by offering it the most favor- 
able conditions for its activity. His aim is to make the yeast 
ferment the sugar as completely as possible, which not only means 
little nourishment left for other organisms, but also a high percent- 
age of alcohol prohibiting their growth. Incomplete fermentation 
on the other hand results in a weak and unstable wine subject to 
a variety of undesirable changes. 

The Wine-yeasts. The alcoholic fermentation of the must is 
caused by small, usually unicellular budding fungi, mostly belong- 
ing to the different varieties of Saccharomyces ellipsoideus. Their 
principal breeding places in nature are the ripe juicy fruits, where 
they multiply abundantly during the fall. Some of them pene- 
trate with the rain to a certain depth into the soil, where a suf- 
ficient number keep alive over winter to repopulate the fruits of 
the following year, to which they are carried by insects, rain- 
splashes or the wind. Their perpetuation is facilitated by their 



BEER, WINE AND LIQUOR 419 

power of forming spores, small resistant cells appearing under 
certain conditions within the vegetative cells. 

The yeast cells contain an enzyme, the zymase, which in 
contact with dissolved sugar transforms it into alcohol and car- 
bonic acid. This fermentation proceeds most satisfactorily at 
medium temperatures, the yeast becoming temporarily inactive 
at a few degrees above the freezing point of the water and perma- 
nently weakened at about 100° F. Even the most vigorous 
yeast can only produce about 13 per cent of alcohol by weight 
and this only under exceptionally favorable conditions. 

Besides the main products of the alcoholic fermentation 
smaller quantities of glycerol, succinic acid and fusel oils are also 
produced by the yeast during fermentation. Apart from the 
glycerol, that may — as far as our present knowledge goes — be 
derived from the sugar, the other by-products have recently been 
shown to originate from amino-acids (e.g., succinic acid from 
glutamic acid and amyl-alcohol from leucine) the nitrogen being 
utilized by the yeast iu the form of ammonia for building up the 
albumen of its own body. In all probability flavoring substances 
are formed by a similar process from other amino-acids, the 
primary products being various alcohols and acids, which during 
the ripening of the wine are further transformed through oxi- 
dation and esterification. 

White Wines. The white wines are produced by fermen- 
tation of grape juice that has been separated from the skins, 
seeds and stems. A fermentation of this kind offers comparatively 
little difficulty, but the resulting wine is decidedly more delicate 
than those fermented on the skins, whence its subsequent treat- 
ment and proper ripening require greater care. 

The fermentation is usually carried on in casks that are filled 
to -J-^- of their capacity with grape juice and the bung hole is closed 
so as to allow the carbonic acid to escape but no air to enter. 
The duration of the fermentation is from one to two weeks, 
depending on the temperature, which usually is 60-70° F., and on 
the quantity of yeast originally present. At the end of the fer- 
mentation the yeast sediment is sometimes stirred up again in 
order to facilitate the complete splitting up of the sugar and the 
reduction of acidity. 

After the fermentation is over the wine is drawn from the lees 
into another cask in which some sulphur has been burned to check 
the further activity of microorganisms. This cask is completely 
filled, tightly bunged and as a rule kept at a temperature of 50- 



420 ELEMENTS OF INDUSTRIAL CHEMISTRY 

55° F. Before the rising temperature of the following spring 
causes a slight revival of the fermentation, the wine is racked off 
from the sediment once more, and this process repeated several 
times during the subsequent ripening period. At each racking 
an oxidation takes place resulting in precipitation of certain 
albuminoids and further development of the flavor, until finally 
the wine has become sufficiently stable to be filled into bottles. 

In the ordinary grades of wine this ripening is generally more 
or less forced by means of a more thorough aeration during the 
racking, artificial clarification (filtration or use of finings), and, 
eventually pasteurization. 

The simplest form of wine filter is a cylindric or conical linen 
bag into which the wine is poured back until it runs clear. The 
more modern filters are closed so as to protect the wine from the 
air. Their filtering material is either pure cellulose or paper- 
pulp, packed into one or more filtering chambers or especially 
prepared asbestos-wool stirred up with a smaller part of the wine 
and pumped into the filter, where it deposits as a uniform layer 
on walls formed of fine wire screens. 

Finings are added to the wine in order to produce a very finely 
distributed sediment of higher specific gravity which will gradually 
settle to the bottom, carrying with it all suspended solid particles. 
For fining white wines isinglass is commonly used. It is soaked 
in water and at last in wine until nearly transparent and then 
vigorously beaten with some more wine eventually under addition 
of tartaric acid, filtered through linen and thoroughly distributed 
into the wine in the cask. One ounce of isinglass can generally 
fine 200-500 gallons of wine within 8-10 days. 

Red Wines. The red wines derive their characteristics from 
being fermented in contact with the skins of red grapes, from 
which they extract not only coloring matter but also a variety 
of other substances, especially tannins. Normal red wines con- 
tain from 0.1 to 0.3 per cent of tannin, while the percentage of 
this substance in white wine does not as a rule exceed 0.02 to 0.04 
per cent. Owing to this high content of tannin the ripen'ng 
of red wines is a comparatively easy matter once the fermentat on 
has been properly carried through, but the presence of the skins 
at the fermentation on the other hand gives rise to several difficul- 
ties during this process. 

The carbonic acid carries the skins to the surface, where they 
form the so-called cap, which must be pushed down repeatedly in 
order to insure proper extraction and uniformity of fermentation. 



BEER, WINE AND LIQUOR 421 

Closed casks are therefore less suitable and in the open tubs, 
which are generally used, there is great danger, however, of 
acetincation owing to the free exposure of the cap to the air. 
To overcome these difficulties the fermenting tubs are often 
provided with removable grates that are held in horizontal posi- 
tion about 5 ins. below the surface of the liquid, thus prohibiting 
the skins from rising to the surface. To insure proper uniformity 
the wine is draw T n off at intervals from the bottom of the tubs 
and pumped back to the surface. 

The temperature during fermentation of red wine is usually 
65 to 85° F. As red wines are mainly produced in southern 
countries it is often difficult to prevent the temperature from 
rising too high, a considerable amount of heat being generated by 
the decomposition of the sugar. Too high temperature not 
only facilitates the growth of various bacteria but also prevents 
the yeast from completing the fermentation, the result being a 
wine of poor quality and easily subject to further deterioration. 
Artificial cooling is therefore often resorted to, water being 
circulated through cooling coils in the tubs or the wine being 
pumped through enclosed coolers. 

After being fermented the red w T ine is drawn off into casks, 
w T hich, however, are only sulphured in exceptional cases, because 
most red wines do not need this protection and would be more 
or less bleached by the sulphurous acid. Red wines are ripened 
in practically the same way as white wines, but less time and 
fewer rackings are required to render them sufficiently stable for 
bottling. 

The red wines are mostly fined with gelatine or white of egg. 
The gelatine is soaked in water over night, dissolved in wine by 
gentle heating, cooled, stirred up with some more wine and added 
to the cask. One ounce of gelatine is required for 50-120 gallons 
of wine. Whites of eggs are often used to fine the better grades 
of red wine, one white for every 8-12 gallons. They are first 
beaten to a foam, pressed through a heavy linen, and then stirred 
up with some of the wine before being added to its bulk. 

Sweet and Dessert Wines. The white and red wines referred 
to above are all dry, i.e., practically all of their sugar having 
been fermented. The sweet wines and the dessert wines on the 
other hand contain unfermented sugar besides a high or even 
very high percentage of alcohol. The typical sweet wines, such 
as Auslese, Rhine wine, sauterne, or tokay, contain much 
sugar, but their alcohol is produced by fermentation and con- 



422 ELEMENTS OF INDUSTRIAL CHEMISTRY 

sequently does not exceed 13 per cent by weight. The dessert 
wines, such as port, sherry, madeira and malaga, are less sweet, 
but generally contain from 15 to 20 per cent by weight of alcohol, 
part of which has been artificially added. 

The Auslese wines and sauternes are produced from grapes 
attacked by a certain mold, Botrytis cinerea, which finds favorable 
conditions for its growth in a foggy, cool climate without too 
much rain. It causes the grapes to shrink and partly to dry 
up, the must being accordingly more concentrated and possessed 
of a peculiarly fine flavor. The fermentation is carried out with 
a view to produce enough alcohol to prevent further changes, 
but since sugar is left unfermented these wines are prone to after 
fermentation, and as a rule need heavy sulphuring to become 
stable. 

In certain territories the dry and warm climate allows the 
grapes to dry up similar to raisins before they are picked. These 
yield a very concentrated must. The tokay wines of Hungary 
are made from such grapes, extracted with normally fermented 
dry wines and pressed. Imitated tokay is made in a similar 
way from ordinary dried raisins or from must concentrated by 
boiling in vacuo. 

The various dessert wines contain more alcohol than can be 
produced by fermentation. An addition of alcohol is therefore 
necessary, and is often combined with an addition of condensed 
must or sugar. The alcohol may be added either at the end of 
the fermentation or at an earlier stage, in the latter case pre- 
venting part of the sugar contained in the must from being 
fermented. The addition is often made step by step, part of 
the total amount required being added at each racking and thor- 
oughly mixed with the wine. During the ripening period the 
dessert wines are kept at a comparatively high temperature and 
freely aerated. This results in the development of the peculiar 
flavor known as madeira flavor. 

Sparkling Wines. The sparkling wines are produced from 
either red or colorless grapes, the juice alone being fermented as 
usual for dry white wines. After being drawn off from the lees 
the wine is racked once more, a too high content of albuminoids 
being eventually decreased by an addition of tannin. The wine 
is blended in large vats or casks with a view to produce a uniform 
product from one year to another, and enough sugar solution 
is added so that a pressure of about 5 atmospheres can develop 
during the subsequent fermentation in bottles. Furthermore 



BEER, WINE AND LIQUOR 423 

a culture of selected pure yeast is often added, and the wine is 
then bottled and corked, preferably in the spring, because the 
rising temperature facilitates fermentation. When bottled the 
wine has a temperature of 65-72° F., but the bottles are kept at 
about 50° F., when the fermentation has started. This tem- 
perature must be kept as constant as possible to avoid breakage. 
The duration of the bottle fermentation varies from one-half to 
two years. When the proper pressure is reached the bottles are 
placed in a slanting position on special stands, their necks being a 
little lower than their bottoms. A short snaking and turning 
movement is imparted to them once a day during about six weeks 
while they are gradually raised to a vertical position neck down. 
In this way the yeast sediment is carried down on the cork, leav- 
ing the wine entirely clear. This process can be greatly facili- 
tated by the use of a proper variety of yeast, i.e., one combin- 
ing a strong fermenting power with a tendency to grow in larger 
clusters. 

The bottles are now taken to the uncorking room and event- 
ually cooled to bind the carbonic acid more firmly. The uncork- 
ing requires a good deal of skill. The operator holds the bottle 
in a slanting position and gradually loosens the cork until it is 
thrown out by the pressure together with the whole sediment. 
At the same instant the bottle must be turned upright and 
preliminarily closed. Some sugar solution is added before the 
bottles are finally corked, the quantity varying greatly according 
to the requirements of the trade. The sugar solution is thoroughly 
distributed by shaking and the bottles preferably kept in stock 
for some time before being consumed in order that the taste be 
more harmonious and the carbonic acid more permanently bound. 

Imitation champagne is made by saturating white wine with 
carbonic acid under pressure in a suitable apparatus, but such 
sparkling wines are generally lacking in life and when poured 
into the glass do not show the same permanent sparkling as those 
made by the slow process of bottle fermentation. 

DISTILLED LIQUORS. Distilled liquors differ greatly in 
flavor and general character, being influenced in these respects 
by the materials and the methods employed in their production. 
Their names vary according to the nation producing them. 
Among the best known distilled or spirituous liquors are: 

Whiskey. Under the term whiskey is understood the potable 
spirit distilled from fermented mashes, made either from malt 
alone or a mixture of malt and unmalted cereals. The latter 



424 ELEMENTS OF INDUSTRIAL CHEMISTRY 

usually are barley, lye, maize (Indian corn), oats and wheat. 
In some countries, chiefly Germany, potatoes are used. The 
malted cereals generally are barley malt, rye malt, wheat malt, 
and in a few instances oat malt. 

Genuine whiskies are of three different types: American, 
Scotch, and Irish. They differ vastly in flavor, body and color. 

American Whiskey. In the United States two distinctive 
types of whiskey are produced, namely, Rye and Bourbon. The 
grain used for manufacturing Rye whiskey is a mixture of rye or 
barley malt and unmalted rye. Bourbon whiskey is made from 
barley malt or wheat malt and maize (Indian corn) . The quantity 
of malt used amounts to from 10 to 15 per cent of the total weight 
of the materials in the lower grades of whiskies, and from 20 to 
50 per cent in the better grades. Few whiskies are made from 
malt alone. 

The taste and general character of the different whiskies vary 
according to the materials employed, their quality — with special 
reference to the malt — and to the methods of mashing, fermenta- 
tion, distillation and aging of the distilled liquor. The finer the 
quality of the materials and the higher the percentage of malt, 
the better will the taste and flavor of the product be. 

Scotch Whiskey. Two different types of whiskey are made in 
Scotland. The one that is the characteristic Scotch whiskey 
is made from barley malt, and is usually termed pot-still whiskey, 
owing to the old-fashioned style of still used in its distillation. 
The other type is called patent -still, or grain whiskey. It is made 
from barley malt and unmalted cereals, mostfy corn imported 
from the United States. Rye and oats also are used. 

The genuine Scotch whiskies are characterized by a peculiar 
smoky flavor and taste, which originate from the malt. This 
is due to the employment of various kinds of peat as fuel for cur- 
ing, namely kiln-drying, the malt. This peculiarity distinguishes 
the genuine Scotch whiskies from all other types. They are 
generally stored about five years, or longer, during which time 
the whiskey acquires a rich, mellow taste and improves greatly 
in flavor. 

Irish Whiskey. Most of the Irish whiskey is of the pot- 
still type. It is usually prepared from 30 to 50 per cent barley 
malt, the remainder being rye, barley, oats, wheat or a mixture 
thereof. The malt is not peat cured and the resulting whiskies 
have a characteristic clean flavor and an ethereal bouquet. They 
are very " dry," namely alcoholic in taste. 



BEER, WINE AND LIQUOR 425 

Kornbranntwein and Schnapps. These two liquors represent 
the most commonly employed distilled products in Germany. 
The former is prepared from malt and unmalted cereals, usually 
rye. Sometimes maize is used and very seldom wheat. The 
general process of manufacture is similar in principle to that 
employed for whiskey. 

Schnapps is usually obtained by diluting rectified alcohol 
manufactured from potatoes. The potatoes, after cleaning, are 
placed in large converters, mixed with the necessary quantity 
of water and heated under a pressure of 30-60 pounds, in order to 
pastify the starch. The mash is then cooled and a small per- 
centage of malt, often green malt, added, so as to invert the 
pastified starch. After inversion is complete, the fermentation 
is conducted in the same way as for whiskey. The process of 
distillation is such that a rectified alcohol results. 

Brandy. Under the name of brandy is understood those 
distilled liquors obtained by the distillation of grape wines, wine- 
lees or grape pomace. The finest brandy on the market is the 
so-called cognac. It represents the brandy distilled from the 
grape wines grown in the department of Charente, France. 
The town of Cognac is situated here and is the sales-point for the 
brandy made in this vicinity. France, with its numerous vine- 
yards, is the home of brandy, but considerable quantities are now 
being prepared in Algiers and in the United States, principally 
California. 

Genuine brandy, being prepared from the finest and purest 
fermented material, namely, grape wine, is conceded to be the 
best distilled liquor known. It is characterized by its very fine, 
smooth alcoholic taste and exquisite flavor or aroma. It possesses 
a rich golden yellow color and contains from 45 to 55 per cent 
of alcohol by volume. Different brandies vary in taste and 
flavor, and the best results are obtained when they are blended 
together by manufacturers or dealers skilled in this art. 

Gin. The word gin is a shortened form of Geneva, which is 
derived from the old French word " Genevre," namely juniper. 
It is the spirit distilled from a mash prepared from malt together 
with unmalted cereals, usually rye or barley, and is flavored by 
an addition of juniper berries during the rectification of the 
distillate. Some distillers at the same time also add a very slight 
amount of oil of turpentine and hops, in order to obtain a more 
characteristic flavor. 

Gin originated in Holland, and even to-day the finest product 



426 ELEMENTS OF INDUSTRIAL CHEMISTRY 

is produced in Schiedam, Holland, and bears the name of " Schie- 
dam Schnapps." In time it was imitated extensively by English 
distillers and such gin is sold under the name of " London Gin." 

Genuine gin is a colorless liquid of delicate flavor and contains 
about 52 per cent of alcohol by volume. It is extensively imi- 
tated, by flavoring diluted alcohol with various essential oils, 
but such concoctions are decidedly inferior in eveiy respect to 
the genuine article. 

Rum. Among the distilled liquors consumed most commonly, 
rum has by far the highest alcohol content. A genuine rum never 
contains less than 70 per cent alcohol by weight (about 78 per 
cent by volume) and sometimes it is as high as 77 per cent. Rum 
is manufactured in Jamaica and other West Indies islands, some 
of the Southern States of the United States, Brazil, Madagascar, 
East India and some of the Indies islands; in fact in any region 
where sugar cane is cultivated extensively. The Jamaica rum 
has the reputation of being the finest in quality. 

The materials employed for preparing rum are the molasses, 
the skimmings (scum or foam) of the sugar kettles and the 
juice of the sugar-cane. The higher grades of rum are made from 
molasses, cane-sugar juice and only very little from the skimmings. 
Lower grades, often called " nigger rum," are prepared chiefly 
from the skimmings and other offal products obtained during the 
boiling and concentrating of the sugar-cane juice when manu- 
facturing sugar. Only little good molasses is employed. Such 
rum has a pronounced burnt, sourish taste and its flavor is coarse 
and rank. 

Slibowitz. This liquor is obtained by fermenting crushed 
plums and distilling the alcohol obtained by the fermentation. 
It is practically colorless and possesses a very clean alcoholic 
taste and odor. Practically no flavor of the plums (prunes) 
from which it was prepared is noticeable. Slibowitz is made 
by very many farmers, especially in Hungary and Servia, who 
use it as the household liquor. 

Arrack. The genuine arrack is a type of brandy containing 
about the same amount of alcohol as found in rum, namely 70 
to 80 per cent by volume. It is prepared mostly in Siam, but 
also in East India, Java and adjacent localities, as well as in 
Jamaica. The materials employed are either (1) toddy, or palm 
wine, (2) rice and toddy, (3) rice and molasses, with or without 
an addition of toddy. 

Toddy, or palm -wine, is obtained by fermenting the sugary 



BEEE, WINE AND LIQUOR 427 

juice of the cocoanut palm. This liquid is subjected to dis- 
tillation in order to obtain the desired alcoholic strength. 

Vodka. This is the national distilled liquor of Russia. The 
genuine vodka is prepared from rye, employing 15 to 20 per 
cent of barley malt or green rye malt in order to saccharify the 
starch. Some of the cheaper grades of vodka are prepared from 
potatoes and corn instead of rye. 

Vodka contains from 40 to 60 per cent of alcohol by volume; 
in fact, it is illegal to sell it if the alcohol is less than 40 per cent. 
The method of distillation is about the same as that used 
for patent-still whiskies. 

Chartreuse. Three different types are on the market, namely, 
green, yellow, and white Chartreuse. They have been prepared 
for centuries by the Carthusian monks, who have zealously 
guarded their secret of production even to this day. Chartreuse 
is prepared from a mixture of aromatic herbs and seeds, and pos- 
sesses a very delicate flavor and taste. 

Benedictine. This cordial is altogether different in taste and 
flavor from Chartreuse. The genuine Benedictine also is pre- 
pared by monks. 

Kirschwasser. This liqueur is colorless in appearance and is 
obtained from cherries. The latter, including the seeds, are 
crushed and allowed to undergo fermentation. The alcohol is 
then distilled. The finished Kirschwasser has a pleasant flavor 
and bouquet, slightly reminding the consumer of ripe cherries. 

Maraschino. This is another cherry cordial distilled from the 
fermented juice of Dalmatian cherries. It is sweetened by an 
addition of sugar-sirup. 

Prune, Peach, Apricot, and Cherry Brandies are prepared 
from these respective fruits by distillation of the fermented juices. 
The distillate is either placed on the market as first obtained, or 
it is sweetened and colored. Sometimes an infusion of the fruit 
in alcohol also is added to the distillate, or the infusion itself is 
placed on the market. They all possess the characteristic flavor 
and aroma of the fruit from which they are obtained. 

Absinthe. This cordial is very popular in France and is pre- 
pared by distilling rectified alcohol or brandy in which worm- 
wood, star-anise, green anise seed, fennel, coriander, angelica-root 
or other aromatics have been macerated for about a week. The 
resulting liqueur is greenish in color and contains a large amount 
of volatile oils. On account of the latter, absinthe becomes 
milky when water is added immediately before drinking it. The 



428 ELEMENTS OF INDUSTEIAL CHEMISTRY 

oil of wormwood has a very powerful effect upon the nervous 
system, and steady tippling of absinthe causes digestive disorders, 
induces vivid dreams and hallucinations, and may finally cause 
paralysis or idiocy. 

Anisette. The aromatic seeds used for its preparation are 
green anise seed, star-anise, and coriander seed. The distillate 
is sweetened and sometimes also receives an addition of orange- 
flower water. 

Creme de Menthe is a sweetened liqueur, the flavor of which 
is obtained from fresh mint leaves, usually peppermint. It 
usually possesses a pronounced green color. 

Creme de Yvette, also called Creme de Violet, has a pronounced 
odor of violets and also is violet in color, artificially obtained. 

Creme de Roses is rose-colored in appearance and is a sweet- 
ened liqueur having a pronounced odor of oil of roses. 

Creme de Vanilla has a strong vanilla taste and odor. 

Crtme de Cacao is obtained by making an infusion of cocoa, 
alcohol and sugar-syrup. 

Curacao. This very fine liqueur is prepared by macerating 
orange peel, especially from Curacao oranges, in rectified alcohol 
for a week or longer. After distillation and addition of sugar- 
syrup and a coloring substance is added. The finest grades are 
prepared in Holland. 

Aquavit. Although this liqueur is not a cordial in the true 
sense of the word, a brief description is placed here. It is gener- 
ally used as an appetizer. Aquavit is manufactured and con- 
sumed extensively in the Scandinavian countries, especially 
Denmark. When the alcohol from grain mashes is rectified, an 
addition of caraway seeds and orange peel is made in order to 
impart their flavors to it. 

Kummel is obtained by distilling alcohol in the presence of 
the herb cumin and caraway seed. An infusion of these in alcohol 
also is made. The product has a pronounced taste and odor of 
the caraway seed and is sweetened more or less according to the 
demands of the trade. It is very popular in Germany. 



CHAPTER XXIII 
TEXTILES 

DEFINITIONS. By the term " textiles " is to be understood 
a class of manufactured articles prepared from " yarns " which 
are continuous threads composed of fibrous materials. These 
fibrous materials, which form the basis of textile manufactures, 
are of various kinds, including animal, vegetable, and mineral 
products; for example, wool, cotton, and asbestos. A fiber is 
really a filament the length of which is comparatively much 
greater than the diameter, and the latter is of almost microscopic 
proportions. This allows of several fibers being twisted together 
by a process known as spinning, so that a continuous and uniform 
thread is produced. Physically, a textile fiber must possess con- 
siderable tensile strength and pliability in order to yield a satis- 
factory thread. In the case of the shorter fibers, such as cotton 
and wool, the surface structure also allows of considerable cohesion 
between the separate fibers when twisted together. Where this 
cohesive property is lacking, as in silk and some of the cruder 
vegetable fibers, the strength of the twisted thread depends on 
the great length of the individual filaments. 

ORIGIN. The textile fibers may be classified with respect 
to their origin in the following manner: 

Animal Fibers, consisting (a) of the hairy covering of various 
animals, principally of the sheep, goat, cow, and camel; and (6) 
of the filaments spun by the silkworm for its cocoon. 

Vegetable Fibers, consisting (a) of the hairy covering of the 
seed of the cotton plant; (b) of the bast or structural part of the 
stem of certain plants, such as flax, ramie, jute, and hemp; (c) of 
the structural part of the leaves of such plants as sisal, agave, 
and certain palms. 

Mineral Fibers, of which the only representative is asbestos. 

Artificial Fibers, such as artificial silk, prepared from solu- 
tions of cellulose derivatives, spun glass, and certain metals 
drawn out to fine filaments. There are also metallized yarns, 

429 



430 ELEMENTS OF INDUSTRIAL CHEMISTRY 

consisting of a core of cotton, linen, or other fiber, coated with a 
finely divided metal and a suitable agglutinant. 

The great bulk of the textile fibers are comprised under the 
first two classes, of which the most typical representatives to be 
considered are wool, silk, cotton, and linen. 

THE ANIMAL FIBERS. In their chemical nature these fibers 
are essentially proteid substances of complex organic structure. 
The basis of wool (and the hair fibers in general) is called keratin, 
a nitrogenous substance containing also sulphur, while that of 
silk is known as fibroin, which is also nitrogenous but does not 
contain sulphur. In their physical structure the hair fibers are 
very complex, being composed of minute cells and provided with 
an external layer or sheath of hard, bone-like tissue or scales. 
Silk, on the other hand, is a continuous filament without apparent 
organic structure. 

THE VEGETABLE FIBERS. The chemical basis of this entire 
class of fibers is cellulose, and as this contains neither nitrogen nor 
sulphur, it presents a marked chemical difference to the albumi- 
nous substance of the animal fibers. In their physical structure 
the vegetable fibers as a class are comparatively simple; in the 
case of cotton the fiber consists of a single elongated cell; with 
the bast and leaf-tissues the commercial fiber consists of a more 
or less complex aggregate of small cells. Cotton in its natural 
state consists of almost pure cellulose, and requires but little 
purification for use in manufacturing; the other vegetable fibers, 
however, are associated with a considerable amount of substances 
other than cellulose and require a rather extensive process of 
purification for the purpose of isolating the pure cellulose fiber. 

WOOL. This fiber is the hairy covering (or fleece) of the sheep. 
It is a growth originating in the skin, springing from a root or 
hair-follicle. In its physical structure the fiber consists of three 
portions: (a) an inner layer of rounded elliptical cells, called the 
medulla, and often containing pigment matter; (6) a surrounding 
region of elongated spindle-shaped cells, called the cortical layer, 
which forms the major portion of the fiber; and (c) an external 
coating of flattened, hard, horn-like cells, or epidermal scales 
arranged in such a manner as to overlap like the scales on a fish. 
This latter peculiarity of structure gives to wool a characteristic, 
microscopic appearance, whereby it may be readily distinguished 
from other fibers (see Fig. 113). The character of fiber pro- 
duced in the fleece varies largely with the breed and cultivation 
of the sheep. The merino sheep (now grown principally in Aus- 




TEXTILES 431 

tralia) gives a long, fine and wavy fiber, much prized for the 
manufacture of high-class clothing fabrics. The majority of the 
wool grown in America (chiefly known by the name of " territory " 
wool) is of shorter staple and coarser in quality. The arrange- 
ment of the epidermal scales also varies considerably with the 
nature of the fiber. With some wools, these scales are prominent 
and the free edge projects considerably, 
giving the fiber a serrated or saw-toothed 
appearance. Wool of this nature is easily 
felted, as the fibers become firmly attached 
to one another by the interlocking of the 
projecting scales. In other varieties of 
wool the external scales lie flat on the 
surface with very little free edge project- 
ing, hence the surface of these fibers is 
smooth and does not readily felt together. 
Another important physical property of 
wool is its waviness. Some wools (espe- Ftg - 113 - 

cially the fine merinos) are very wavy, 

and the waves (or crimps) occur with great regularity through- 
out the entire length of the fiber; other wools are stiff and 
straight with lictle or no waviness, or have very irregular waves. 
The wavy structure of the fiber enhances its spinning quality, 
as it allows of a greater coherence among the fibers when they 
are twisted together. A yarn composed of such fibers also 
exhibits greater resiliency and sponginess as well as elasti- 
city. 

SCOURING OF WOOL. In its natural state in the fleece wool 
is contaminated with a number of impurities. These may be 
classified as follows: 

(a) Wool grease, which occurs in large quantities as an external 
coating on the fiber; it is a natural exudation of the sheep and 
serves as a protection to the fiber, preventing it from becoming 
felted and mechanically injured. It differs from other animal 
fats in that it does not consist of the glycerides of the fatty 
acids, and is very difficultly saponifiable with caustic alkalies. 
Wool grease possesses more the chemical properties of a wax, 
as it is composed mostly of the higher solid alcohols known as 
cholesterin and isocholesterin both in the free state and as esters 
with the fatty acids. Though insoluble in water and not saponifi- 
able by alkalies, cholesterin is easily emulsified, a property on 
which is based the usual method of wool scouring. Wool grease, 



432 ELEMENTS OF INDUSTRIAL CHEMISTRY 

however, is easily soluble in naphtha and other volatile sol- 
vents. 

(6) Suint, or dried-up perspiration, consisting largely of potash 
salts of organic acids, and soluble in water. 

(c) Miscellaneous dirt, such as dust, sand, vegetable matters, 
tar, etc. 

Before the wool fiber can be used in manufacturing processes 
it must first be cleansed from the adhering impurities. This is 
accomplished by scouring the dirty and greasy wool in a warm 
soap solution, to which more or less soda ash is added. The 
temperature of scouring should not be above 140° F., else the 
fiber will be injured by the action of the alkali. The wool grease 
is easily emulsified by the alkaline soap solution, whereas the 
suint is dissolved by the water, the other impurities being removed 
by the mechanical action of the water. After scouring in the 
soap solution the wool is thoroughly rinsed in warm water, and 
finally squeezed and dried. Another form of wool scouring, 
known as the solvent process, is becoming of great importance 
in this country. The greasy wool is treated with solvent naphtha 
in closed kiers, and the resulting solution of wool grease is trans- 
ferred to stills where the naphtha is recovered and the wool 
grease is obtained as a by-product. The latter may be further 
purified and utilized for the preparation of lanolin compounds. 
The degreased wool is next treated with a dilute warm soap 
solution to remove the suint and dirt. This process leaves the 
fiber in a much better condition and the recovered grease is of 
sufficient value to pay for the cost of scouring. 

MECHANICAL TREATMENT OF WOOL. After wool has 
been scoured and dried the next step is to convert it into yarn. 
In the first place, according to the quality of yarn desired, a 
close selection of the required grade of wool is made. This 
is the function of a special branch of the industry known as 
wool grading and sorting. Wool is first graded with reference to 
the breed of sheep, such as full-blood merino, territory, half- 
blood, etc. This has reference chiefly to the fineness and length 
of staple. The long stapled wools are suitable for combing and 
are used for the preparation of worsted yarns; the shorter stapled 
varieties are carded and made into woolen yarns. In the combing 
process the shorter fibers (noils) are removed from the long ones, 
leaving the latter to form what is called tops, a form of preparation 
previous to the spinning of the yarn. As the character and equal- 
ity of the fiber varies considerably at different parts of the same 



TEXTILES 433 

fleece, wool is further graded by sorting the fleece into its distinc- 
tive portions, such as the loin, back, neck, legs, etc. Usually 
the fleece is sorted into nine portions. The grading and sorting 
of the fleece is made previous to scouring. 

In the preparation of yarn the first step is combing (for long 
staples) or carding (short staples). This is for the purpose of 
removing undesirable matters, such as short fibers, adhering 
impurities, etc., and also to lay the fibers in a parallel direction 
and bring the wool into a ribbon-like form so as to permit of the 
subsequent spinning operations. These latter processes consist 
in further paralleling the fibers and reducing the thread to the 
desired size by drawing out and twisting. 

Chemical Treatment of Wool. (1) Bleaching. The 
wool fiber in its natural state contains more or less of a yel- 
lowish-brown pigment. In some cases this pigment becomes 
greatly accentuated and the fleece may be dark brown or even 
black in color, but these occasional " black sheep " are of 
rather rare occurrence. Where it is desirable to have a per- 
fectly white fiber either for purposes of dyeing delicate tints or 
for white goods, it becomes necessary to bleach the wool. There 
are two general methods in use at present for this purpose. In 
the first, sulphurous acid, SO2, is used as the active bleaching 
agent. The well-scoured and moistened woolen material is placed 
in a suitable room and subjected to the prolonged action of fumes 
of burning sulphur, the time required for complete bleaching being 
from eight to twenty-four hours, depending on the nature and 
texture of the material. The process is termed " stoving," from 
the so called stove in which the sulphur is burnt. The bleaching 
room must be so constructed as not to permit of the condensed 
acid liquor dropping on the goods, which would otherwise be 
spotted and injured. This process is known as the " gas " or 
" dry " method of bleaching. After the bleaching is finished 
the wool is rinsed in a water containing a minute quantity of a 
blue or bluish -violet coloring matter for the purpose of tinting 
the white so as to furnish a more pleasing color to the eye. A 
" wet " process of bleaching may also be employed, the wool 
being steeped in a dilute solution of sodium bisulphite for some 
hours, and then passed through a bath of dilute sulphuric acid. 
The bleached white obtained on wool with sulphurous acid does 
not appear to be permanent, as prolonged exposure to the air 
will cause the yellow natural color to return. This has been ac- 
counted for by assuming that the sulphurous acid merely reduces 



434 ELEMENTS OF INDUSTRIAL CHEMISTRY 

the natural pigment to a colorless compound which becomes 
reoxidized on exposure to the air, resulting in the formation 
again of the original pigment. 

A second process for the bleaching of wool which is coming 
into considerable favor, more especially for fine goods, is that 
which employs sodium peroxide as the bleaching agent. Hydro- 
gen peroxide is also employed to a considerable extent in bleach- 
ing. It is probably somewhat more expensive to use than sodium 
peroxide, but does not offer the disadvantages of the latter in 
the preparation of the bleaching liquor, which in the case of 
hydrogen peroxide is also free from sodium sulphate. Sodium 
peroxide, Na202, when dissolved in water acidulated with sul- 
phuric acid yields a solution of sodium sulphate and hydrogen 
peroxide: 

Na 2 02+H2S04 = Na 2 S04+H 2 02. 

The hydrogen peroxide in contact with organic substances 
readily decomposes with liberation of nascent oxygen: 

H 2 2 = H 2 0+0, 

and the latter quickly decomposes and destroys the coloring 
matters in wool. 

Wool may also be bleached by treatment with a cold dilute 
solution of potassium permanganate. The pigment in the fiber 
is rapidly destroyed by the strong oxidizing action of this chem- 
ical, but the resulting decomposition of the permanganate pre- 
cipitates a brown hydroxide of manganese on the fiber, hence it 
is necessary to pass the wool through a second bath containing a 
weak solution of sodium bisulphite, which removes completely 
the deposit of manganese compound and leaves the wool per- 
fectly white. Oxalic acid will also have the same discharging 
effect on the brown oxide of manganese, and is sometimes em- 
ployed in place of sodium bisulphite. This method gives a very 
rapid process for bleaching, but it is rather costly. 

The Minor Animal Fibers. In addition to wool there 
are also a number of other animal hair fibers employed to a limited 
extent in the manufacture of textiles. The woolly fibers of dif- 
ferent species of goats are utilized in much the same manner as 
wool itself. Mohair is obtained from the Angora goat. The 
fiber is long, fine, smooth and highly lustrous. It is largely used 
for the manufacture of plushes, braids, and linings. Cashmere, 



TEXTILES 435 

alpaca and llama are also fibers from species of goats. All of 
these animal hair fibers are similar in chemical composition to 
wool; their physical structure is also very similar. 

SILK. Though silk is also an animal fiber and somewhat 
similar to wool in its general chemical properties, it differs very 
widely from that fiber in its plrysical structure and properties. 
The silk fiber is a fine continuous filament spun by the silkworm 
in the preparation of its cocoon. The fiber as spun by the cater- 
pillar consists of two filaments composed of a proteoid substance 
called fibroin and surrounded and cemented together by a glue- 
like substance known as sericin or silk-gum. The silkworms 
are cultivated principally in China, Japan, Italy and southern 
France. Their chief food consists of the leaves of the mulberry 
tree, hence the caterpillar is known as the mulberry silkworm, 
or Bombyx mori. The cocoons are irregularly ovoid in shape and 
the length of the fiber in them varies from 350 to 1200 meters, 
while its average diameter is 0.018 mm. The silk fiber as used 
in manufacturing is prepared by reeling from the cocoons. When 
the cocoons have been completed by the silkworm they are 
collected and heated in an oven to a temperature of 60 to 70° C. 
for the purpose of killing the pupa within. Or, the cocoons 
may be steamed for a few minutes, which serves the same purpose. 
The cocoons are then sorted for size, color, damage, etc., so as 
to obtain a uniform product. They are then placed in a basin 
of warm water, which softens the enveloping silk-glue and permits 
of the unwinding of the cocoon thread. The fibers from several 
cocoons are brought together and passed over a suitable reel, 
where they are slightly twisted together to form a thread of suffi- 
cient size for weaving. The adhering silk -glue becomes hard- 
ened again, so that the thread presents a uniform appearance. 
This silk is reeled into skeins of convenient size and comes into 
trade as raw silk. Owing to the presence of the silk-glue it is 
stiff and wiry and translucent in appearance. Some varieties 
are of a creamy white color, while others are quite yellow. This 
yellow .color, however, exists only in the silk-glue and is removed 
along with the latter. Organzine silk is prepared from the high- 
est grade of cocoons, and by reason of its superior strength it is 
employed for warps. Tram silk is weaker and is used for filling. 
In the reeling of silk a large amount of waste is produced. This 
is scoured in a solution of soap and soda in order to remove the 
silk-glue, and the residual fiber is then carded and combed and 
is used for the preparation of spun silk. 



436 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Bleaching of Silk. For most purposes silk is sufficiently white 
without bleaching, but where very delicate tints are to be dyed 
or where a very pure white fabric is desired, it is necessary to 
bleach out the slight tint of yellow to be noticed in natural silk. 
Silk may be bleached in much the same manner as wool, using 
either the sulphurous acid or the sodium peroxide process. 
The latter method is to be preferred in the case of silk, as it fur- 
nishes a nicer product, and the bleach is not liable to become 
yellow again on exposure. The extra cost of this process is not 
a drawback when employed for silk as when used for wool, as 
the comparative value of the fiber itself is far greater. Silk was 
formerly also bleached by treatment with dilute cold solutions 
of aqua regia, but as this process was very liable to cause injury 
to the fiber unless very skilfully conducted, it is not now employed 
to any extent. 

COTTON. The cotton fiber consists of the hairy covering 
of the seeds of the cotton plant, or gossypium. There are a large 
number of species and varieties of the cotton plant, the principal 
of which are the following: 

Gossypium barbadense, producing silky and long-stapled 
fibers, the principal representatives of which are the Sea Island 
cotton of the Southern Gulf States, Egyptian cotton and Peruvian. 

Gossypium hirsutum, which includes most of the cotton grown 
in the United States and forms the great bulk of the cotton used 
in trade. It is known as upland, peeler or simply American 
cotton. 

Gossypium herbaceum, including the majority of the cotton 
grown in India and China, as well as the small amount which is 
grown in Italy. The fiber is very short and inferior to that of the 
two preceding varieties. 

Gossypium arboreum comprises most of the cotton in Asia 
Minor. This variety grows to the dimensions of a tree in contra- 
distinction to the other varieties, which are all shrubs. The 
fiber is of poor quality, being short and coarse and of a greenish 
color. 

The seed hairs of cotton are developed in a boll as the fruit 
of the plant ripens, and when maturity is reached the boll 
bursts open, liberating a fluffy white mass of fibers. These fibers 
are firmly attached to the surface of the seed, and after the cotton 
is picked from the plant the fiber must be detached and separated 
from the seed by a process known as ginning. The ginned fiber 
is then baled and distributed to the spinning mills. The seed 



TEXTILES 437 

which is left now forms a valuable by-product of the industry. It 
is first subjected to a second process of ginning for the purpose 
of removing the short undergrowth of fibers known as neps or 
linters, and these are used in the manufacture of wadding and 
cotton batting. The cleaned seeds are then hulled, and from 
the separated meal the oil is extracted bj^ cold and hot pressing 
and steaming. The cotton seed oil so obtained is a very valuable 
product, the finer qualities being used for salad oils and other 
culinary purposes, while the lower grades are extensively used 
for soap-making. The residual meal is used as a cattle food, 
and other residues find use as fertilizers. 

Before being utilized by the spinner, cotton is graded with 
respect to length and fineness of staple, color, cleanliness, and 
other qualities. The value of the fiber is determined by this 
classification, the basis being what is known as " middling " 
cotton, the various grades going up and down from this standard. 

Physical Properties of Cotton. The cotton fiber consists of a 
single cell, narrow and elongated, with one end fastened to the 
seed and the other tapering to a point. During its growth it is 
tubular, being cylindrical in shape with comparatively thin cell- 
walls and an inner canal or lumen. When the fiber ripens, the 
sap in the inner canal is absorbed, the cell-walls collapse, leading 
a flat ribbon-like fiber with thickened edges. By the unequal 
drying of the fiber it becomes twisted spirally on its axis. These 
spiral twists give to cotton its good spinning qualities, for when 
twisted together the fibers cohere to one another to give a strong 
thread. The different varieties of cotton exhibit considerable 
variation in length and fineness of staple. Sea Island cotton 
has an average length of about 1.6 ins. and a diameter of 0.00065 
in. Ordinary American cotton varies from 1.5 to 0.75 in. in 
length and has a diameter of about 0.00075 in. Egyptian cotton 
has a staple slightly shorter than Sea Island, and of about the 
same fineness. The South American and Indian cottons are 
comparatively short and coarse, averaging about 1 in. in length 
and 0.00085 in. in diameter. The physical character of the 
fiber in any lot of cotton is very variable, hence in manufacturing 
it is necessary to separate the short fibers from the long by a 
process of combing or carding; the longer fibers being used for 
the better grade of yarns and the shorter fibers for the coarser 
yarns. The degree of ripeness of the fiber also determines its 
general character; unripe fibers have a very attenuated cell- wall 
and consequently are weak and brittle. The mature fiber has 




438 ELEMENTS OF INDUSTRIAL CHEMISTRY 

a thicker wall and a much greater strength. Sea Island, American 
and Indian cottons contain very little natural pigment, being 
quite white in appearance; the chief varieties of Egyptian cot- 
tons, however, are rather highly tinged with a brownish color, 
which is quite distinctive. The micro- 
scopic appearance of cotton is quite char- 
acteristic and serves to distinguish it 
readily from other fibers either of animal 
or vegetable origin (see Fig. 114). The 
flat, twisted, ribbon-like appearance is very 
noticeable. 

Bleaching of Cotton. On account of 
the nature and the small amount of 
impurities present in the raw fiber, cotton 
Fig. 114. does not require a previous scouring 

operation to fit it for manufacturing 
processes. Previous to dyeing, however, cotton must be 
scoured or " wet-out " for the purpose of removing the waxy 
coating so that the fiber may be able easily to absorb the dye 
solutions. This is accomplished by boiling the material in a 
weak solution of caustic soda, soda ash, soap, or Turkey-red oil. 
When cotton is to be bleached, not only the waxy coating must be 
removed to permit of wetting-out, but as far as possible all of 
the impurities on the fiber must be removed. This process is 
termed " boiling-out." Cotton may be bleached in any form 
of its manufacture. It is occasionally bleached in the loose state 
before spinning, in which case special machines are employed 
which allow of the bleaching liquors being circulated through 
the cotton without motion of the fibers, so as to avoid matting 
and injury to the latter. Instead of boiling-out with alkalies, 
cold water is circulated through the cotton under pressure, which 
has the effect of removing the majority of impurities on the fiber 
without materially dissolving the cotton-wax. Cold bleaching 
liquors, wash waters, acid solutions, etc., are then circulated in 
the same manner. The result is a bleached cotton which still 
retains considerable wax,- so the spinning qualities of the fiber 
are not materially injured. If loose cotton is thoroughly boiled- 
out and bleached in the usual manner, the fiber will be harsh and 
will not spin well. Cotton waste and linters are also bleached 
largely in the loose state for the preparation of absorbent cotton. 
In this case, as it is not necessary to retain the spinning qualities, 
but to make the fiber as pure and as absorbent as possible, a very 



TEXTILES 439 

thorough boiling out with caustic soda is given before the bleach- 
ing. 

Cotton yarn is very extensively bleached, both for white goods 
and as a preparation for the dyeing of delicate shades. The yarn 
in the form of skeins is usually bundled together and systemati- 
cally packed into a closed iron kier. The latter is so constructed 
as to permit of the circulation of a boiling alkaline solution under 
pressure (5 to 10 lbs.) through the yarn. The boiling-out solu- 
tion usually consists of a mixture of caustic soda and soda ash. 
Sometimes so-called " bleaching assistants " are used; these mostly 
consist of soda ash mixed with a small amount of caustic soda 
and sodium silicate. For the proper boiling-out of the yarn it 
is essential that the liquor be circulated evenly and thoroughly 
through the goods. The amount of alkali employed is about 2 
to 3 per cent on the weight of the yarn, and the time of boiling 
varies from one and one-half to eight hours, depending on the kier 
employed and the pressure. Overboiling by the use of too much 
alkali or too prolonged a treatment will render the yarn harsh 
and brittle and also cause yellow stains. The presence of air 
in contact with the superheated yarn in the kier will also cause 
oxidation, resulting in weak places and stains. After the yarn 
has been boiled-out it is washed with fresh water, usually in the 
same kier, and then worked in a cold dilute solution of chloride 
of lime (bleaching powder or chemic) at 1-J- to 2° Tw. For this 
purpose the yarn is either hung in sticks and steeped in the 
chemic solution in ordinary dye-house vats, or better yet it is 
placed in a machine where it may be automatically worked in 
the solution. The treatment with the bleaching liquor usually 
lasts from three-quarters to one hour. The yarn is then rinsed 
in fresh water and next soured by treatment with a cold solution 
of sulphuric acid at about 1° Tw.; hydrochloric acid may also 
be used*. The acid treatment is for the purpose of decomposing 
the lime compounds retained by the fiber. Where sulphuric acid 
is used calcium sulphate is formed, which is easily removed in the 
subsequent washing. Hypochlorous acid and free chlorine are 
also liberated in the fiber, which furthers the first bleaching action 
of the chloride of lime solution. This is evidenced by the fact 
that the cotton becomes much whiter in appearance when treated 
with the acid, also the presence of chlorine is to be noted from its 
pungent odor. When hydrochloric acid is used for the souring, 
the very soluble calcium chloride is formed, which is very easily 
removed from the cotton by washing; otherwise the action of the 



440 ELEMENTS OF INDUSTRIAL CHEMISTRY 

acid is the same. After the acid treatment, it is necessary to give 
the cotton a very thorough washing to remove as completely as 
possible the residual acid liquor and the lime compounds from the 
fiber. If this is not done the yarn will be harsh and tender after 
drying. The washing should be continued until the yarn shows 
no indication of acid when tested with blue litmus paper. Finally, 
the yarn is treated in a dilute lukewarm solution of soap or other 
suitable finishing compound, and if a bluish tone of white is 
desirable a suitable bluish-violet coloring matter is added for tint- 
ing purposes. The bleaching process with chloride of lime is 
an Oxidation process; the chlorine itself, which is the active con- 
stituent of the bleaching powder, does not directly destroy the 
coloring matter in the fiber. In the presence of water, how- 
ever, the chlorine liberated in a nascent condition from the 
chloride of lime reacts with the formation of oxygen, and it is 
the latter which acts on the coloring matter. 

Skein yarn may also be bleached by being linked together in 
the form of a long chain and run continuously through machines 
provided with squeeze rollers. Yarn in the form of prepared 
warps may also be bleached in a similar manner. There are also 
special machines for the bleaching of cotton slubbing and yarn 
in the form of cops and tubes, the yarn or slubbing being wound 
on perforated tabes and so arranged on the machine that the 
bleaching liquors are forced through the cotton either by means 
of vacuum suction or pumps. 

Cloth bleaching is the principal method, however, for the 
bleaching of cotton. There are several methods of carrying out 
this form of bleaching depending on the ultimate use to which the 
goods are to be put. When the cloth is destined to be sold as 
white muslin the process is known as the market bleach; when the 
cloth is subsequently to be dyed with alizarin colors (especially 
red), a so-called Turkey-red or bottom bleach is given; whereas 
cloth intended for printing is given the madder bleach. These 
names are quite old in their application and are falling into 
disuse as characteristic terms. In bleaching for white goods 
for the market it is desirable to obtain a clear white color with 
a bluish tint, and the appearance of the goods also depends to a 
considerable degree on the finishing processes given the cloth 
after bleaching. The Turkey-red bleach is only for the purpose 
of providing a white bottom for dyed colors so that the latter 
will appear bright and clear. The bleaching required of print 
cloth is by far the most complete and thorough, as it is neces- 



TEXTILES 441 

sary to remove all impurities from the goods so as to leave the 
cotton not only white in color but also in the form of chemically 
pure cellulose so that the printing colors may be properly applied. 
A general outline of the various processes in this method of bleach- 
ing is as follows: 

Marking. The cotton pieces as they come from the loom are 
stitched together and marked with a special ink capable of 
resisting the bleaching operations so they may be subsequently 
identified. 

Singeing. The cloth is passed rapidly through a series of 
gas jets so as to burn off the loose fibers and lint from the sur- 
face. The singeing may be done on one side only or on both 
sides as required. Instead of being passed through gas jets the 
cloth may be passed over curved copper plates heated to redness, 
or over a heated revolving copper roller. Singed cloth gives a 
clear, even surface, so that fine and delicate patterns may be 
sharply and clearly printed. 

Gray Wash. This is a preliminary wetting out in water and 
has for its purpose the removal of much of the external dirt 
as well as the softening and removal of much of the sizing used 
on the warp yarns in weaving the cloth. This operation is 
frequently omitted. 

Boiling-out. This is a similar operation to the boiling-out 
of cotton yarn. It is usually conducted in large closed iron 
kiers provided with a suitable mechanism for the circulation of 
the liquor through the goods. The boiling is usually conducted 
under pressure (from 10 to 80 lbs.) for from six to eight hours. 
It was formerly the custom to give a first boiling with milk of 
lime (lime oil). The goods were passed through a solution of 
milk of lime and without squeezing were packed into the kier; 
sufficient water was next introduced and the kier boiled with 
superheated steam. The lime boil was considered necessary 
to decompose the fatty matters in the cotton with the formation 
of a lime soap, and also to convert the starch (or other dressing 
materials on the cloth) into a soluble form. Of late years, 
however, the lime boil is being dispensed with as a preliminary 
operation, and the boiling-out is done in one operation with 
caustic soda. When the lime boil is used it is necessary to give 
a thorough washing to the goods and then to pass them through 
a weak bath of sulphuric acid (1° Tw.), known as the gray sour. 
This is for the purpose of dissolving out the lime compound 
in the fiber as well as any iron stains which may have formed 



442 



ELEMENTS OF INDUSTRIAL CHEMISTRY 



in the kier. After the acid treatment another thorough washing 
process is required. After the gray sour the goods are given a 

second boiling in the kier (Fig 115) 
with caustic soda; generally mix- 
tures of caustic soda, soda ash, and 
rosin soap are employed, and from 
two to three boilings are given. 
These boilings remove all of the 
waxy and fatty matters and most of 
the pectin compounds in the fiber. 
The use of rosin was once considered 
essential to the perfect scouring of 
cotton for purposes of print-cloth. 
At the present time, however, the 
tendency is to omit the rosin boil: 
in fact, the boiling-out is reduced 
to the single operation of treating 
in the kier with caustic soda solu- 
tion. 

Washing. After the boiling-out, 
in whatever manner it may be con- 
ducted, the goods are very thor- 
oughly washed in order to remove, 
as far as possible, all of the decom- 
posed impurities and residual alkali. 
The washing is conducted in special forms of washing machines 
(Fig. 116) and well flushed with fresh water. 

Chemicking. This is the general term given to the treatment 
with the solution of bleach- 
ing powder. The strength 
of the solution employed is 
usually 1J to 2° Tw., and 
the liquor should be clear 
and free from undissolved 
particles or sediment. The 
damp cloth is saturated with 
this chemic solution, passed 
through squeeze rolls, and 
then piled up and left ex- 
posed to the air for some 

hours. This allows the carbonic acid of the air to react 
with the bleach liquor with the formation of free hypochlorous 




Fig. 115. 




Fig. 116. 



TEXTILES 443 

acid which destroys the coloring matter present through its 
strong oxidizing action. Care must be had not to allow the 
oxidizing action to proceed too far or the cotton fiber itself will 
be attacked and weakened by the formation of oxy cellulose. In 
some methods of bleaching, instead of exposing the cloth to the 
action of the air, it is steeped in the solution of bleaching powder 
for some hours, or the cloth is packed in suitable kiers and the 
chemic solution is circulated through it by means of pumps. 

Souring. After treatment with the chemic solution the cloth 
contains a considerable amount of lime compounds and unde- 
composed chlorine derivatives. The souring, or treatment with 
a dilute solution of sulphuric acid 1° Tw., is for the purpose of 
removing or decomposing these compounds. The cotton also 
becomes much whiter in color after the treatment with acid, 
hence this process is known as the white sour (in contradistinction 
to the gray sour when a lime boil is used). Instead of using 
sulphuric acid for souring, hydrochloric acid is sometimes 
employed, as the lime salt with this latter acid is much more 
soluble; hence much easier to remove from the fiber. After 
souring a very thorough washing must be given the cloth in order 
to remove all salts and acid residue. 

Finishing. The final operation in bleaching cotton cloth is 
to give it a finish suitable to the use for which it may be intended. 
In the case of a market bleach, the cloth must be tinted to a 
proper tone of bluish white and also be starched and calendered 
to give it a smooth and polished surface. Cloth intended for 
dyeing, of course, is not tinted, and receives its special finish after 
it is dyed. Print-cloth is also not tinted, and it is finished in 
the printing operation. 

LINEN. This is next to cotton as a vegetable textile fiber. It 
is obtained from the bast of the flax plant, and differs consider- 
ably from cotton in its structure and appearance. In preparing 
the fiber the entire plant is taken and put through a rippling 
machine for the purpose of removing the leaves, seeds, etc. 
The cleaned stalks are then subjected to a process known as 
retting for the purpose of decomposing the woody tissue and 
dissolving the resinous and gummy matters so that the free 
fiber may be obtained. Retting is essentially a fermentation 
process, and a number of different methods are employed. 
The two chief methods are: (1) steeping in stagnant water. 
The flax straw is tied into convenient bundles and laid down 
in pools of soft water. Fermentation rapidly sets in, and 



444 ELEMENTS OF INDUSTRIAL CHEMISTRY 

when the woody tissue has been decomposed, but before the fiber 
itself is attacked, the bundles are removed and spread out on 
the grass for a number of days, where they may be exposed to 
the combined action of sunlight and air. 

The pulpy stalks are then passed through special breaking 
and scutching machines for the purpose of breaking up and re- 
moving the decomposed matters and leaving the fiber free and 
clean. Flax produced in this manner has a rather dark grayish- 
brown color, as the coloring matters formed during the retting 
process are not removed. The majority of the Irish flax and 
some of the Russian flax is retted in this manner. (2) Steeping 
in fresh running water (in streams) is another method of retting 
by which most of the French and Belgium flax is made. The 
bundles of flax straw are submerged in the streams by means of 
crates. The fermentation proceeds more slowly than by the first 
method, but the coloring matters are removed by the running 
water, so the final product is much lighter in color, and the fiber 
is of a superior quality. Flax may also be retted by exposing 
the stalks for a number of weeks to the action of dew. There 
have also been a number of " improved " chemical methods 
proposed for the retting of flax, chiefly with the purpose of hasten- 
ing the fermentation and obtaining a brighter and clearer fiber, 
but none of these nave proved to be of any value. 

The linen fiber as it appears in trade is in the form of long, 
rather coarse, filaments of a silver or brownish color. These 
fibers consist of a number of comparatively 
small elongated cells cemented together by 
a glutinous intercellular substance. The 
individual fiber cells are about 1 to 2 ins. 
in length and from 12 to 25 /* in diameter. 
The fiber is cylindrical with thick cell- 
walls and a narrow internal canal. Under 
the microscope the fiber shows the pres- 
ence of peculiar cross-marks resembling 
joints or dislocations (see Fig. 117). 
FlG iYi m In its chemical properties linen is very 

similar to cotton, but its cellulose is less 
pure owing to the intercellular substances present. 

Linen is bleached in the same general manner as cotton, but 
as the fibers are more or less disintegrated into the individual 
cells by the bleaching process, fully bleached linen is much weaker 
than raw linen. On this account, linen is generally only par- 




TEXTILES 445 

tially bleached. In its general characteiistics linen is stronger 
than cotton but less elastic; it is a better conductor of heat, 
hence linen garments are colder than those of cotton. Linen 
also has a higher degree of luster than cotton. 

JUTE. This fiber is without doubt next in commercial and 
technical importance to linen. It is also a bast fiber obtained 
from the stalks of Cor chorus capsularis, or Jew's mallow, growing 
in tropical and subtropical countries. The majority of the jute 
of commerce comes from India and the East Indian Islands. 
The fiber is prepared from the stalks by a simple retting in water, 
the fiber separating rather readily from the other tissues. As 
it appears in trade the fiber is from 4 to 7 ft. in length, usually 
of a yellowish-brown color, though some qualities are of a silver- 
gray color. It has considerable luster and a high tensile strength. 
The cell-elements of the jute fiber are rather small, being about 
1.5 to 5 mm. in length and 20 to 25 ix in diameter. The fiber is 
composed of a rather large number of these cell elements cemented 
together. A cross-section of the fiber shows these cells to have a 
polygonal outline. The microscopic appearance of the jute 
fiber differs from that of linen in not exhibiting the peculiar 
jointed ridges running across the fiber. 

In its chemical composition and properties, jute differs essen- 
tially from the other vegetable fibers. Instead of being composed 
of relatively pure cellulose it appears to consist almost altogether 
of a modified form of cellulose known as ligno-cellulose or bastose. 
This is shown by the fact that the jute fiber gives a yellow colora- 
tion when tested with iodin-sulphuric acid reagents, whereas 
ordinary cellulose gives a blue color. Owing to its different chem- 
ical composition, jute behaves quite differently with the various 
classes of dyestuffs, as it combines directly with both acid and 
basic dyes, whereas cotton and linen require mordants for these 
colors. 

The Minor Vegetable Fibers. There are a number of 
vegetable fibers which are largely used for the manufacture of 
cordage, mats, etc., and which can scarcely be termed textile 
fibers in the sense of being utilized for woven fabrics. Hemp 
and sisal are the principal fibers used for cordage. The former 
is a general name for a large number of commercial fibers of 
similar physical appearance and properties, and obtained from a 
number of different plants. Sisal is a fiber obtained from the 
leaf tissues of the agave and other similar plants. Ramie or 
China-grass is a bast fiber obtained from species of the nettle 



446 ELEMENTS OF INDUSTRIAL CHEMISTRY 

plant. It is a fine white and very strong fiber which would be 
very valuable commercially except for the difficulty with which 
it is obtained from the plant and from the fact that the surface 
of the fiber is so smooth that it lacks cohesion in spinning. 

ARTIFICIAL SILK. This is a fiber which is attaining consider- 
able commercial value. It is a cellulose fiber artificially prepared 
from suitable solutions of cellulose by forcing the liquid through 
fine orifices and coagulating the cellulose as it emerges in the form 
of a delicate thread. There are a number of methods at present 
used for the production of this fiber, among which the following 
are the most important: (1) Pyroxylin or chardonnet silk, pre- 
pared from a solution of guncotton in a mixture of alcohol and 
ether; as the thread is formed the solvent is evaporated and the 
nitrated cellulose becomes coagulated into a continuous filament. 
This thread is subsequently denitrated by treatment with solu- 
tions of nitric acid, ferric chloride, and ammonium phosphate. 
(2) Cupra-ammonium silk is prepared from solutions of cellulose 
in the copper-ammonium sulphate solvent known as Schweitzer's 
reagent. The thread is coagulated and the metallic salts removed 
by a treatment with a solution of sulphuric acid. (3) Viscose 
silk is prepared from a solution of viscose or cellulose thiocar- 
bonate, the thread being coagulated by passing through a solu- 
tion of ammonium sulphate, and subsequently washed very 
thoroughly to remove the sulphur compounds that are formed in 
the decomposition of the viscose. These artificial silks resemble 
true silk very closely in general appearance, possessing even a 
higher luster than the latter. The fiber, however, is more wiry 
and harsh in nature, and its strength and durability is consider- 
ably below that of true silk. The strength of artificial silk is also 
greatly lessened when wetted with water. This fiber, however, 
has a large use in the manufacture of braids, dress trimmings, 
passementerie, and ornamental fabrics of various kinds where 
a high luster is especially desirable. Artificial silk is dyed in the 
same manner as cotton. 

Yarns for textile purposes have also been prepared from paper 
pulp, the general process, being to cut the thin sheet paper pulp 
into narrow strips, and then twist into yarns. Such products 
aie Silvaline and Textilose yarns and fabrics. 



CHAPTER XXIV 
DYESTUFFS AND THEIR APPLICATIONS 

TEXTILE COLORING. Textile coloring may be defined as 
the process or combination of processes used to fix a color or colors 
uniformly, and more or less permanently, upon textile material. 
It includes both dyeing and printing. 

DYEING. The term dyeing is sometimes given almost as 
broad an interpretation as textile coloring, but to be specific, 
it should include only those processes in which the entire body 
of the material being colored is immersed in the coloring bath, 
a greater or less period of the time required for the coloring. 

TEXTILE PRINTING. Textile printing is a process by means 
of which the coloring matters applied may be confined, by use of a 
printing machine, to certain portions of the material, thus pro- 
ducing a definite colored design. The necessary dyestuffs and 
chemicals are made into a paste, with starch, dextrine, or other 
gums, and applied to the cloth by means of copper rollers, one 
for each color, the cloth being finally subjected to special aging 
and drying processes. By this method it is possible to produce 
prints containing ten or more different colors. 

Compounds Used by the Textile Colorist. The 
chemical compounds used by the textile colorist may be divided 
into two classes: 

(1) Those which possess no coloring power, but which are 

instrumental in the fixation or development of 
coloring matters upon the fiber. 

(2) Those which are true coloring matters. 

First Class. Compounds Instrumental in the Fixation of Color- 
ing Matters upon the Fiber, although Possessing no Coloring Power 
Themselves. The compounds included under this heading are 
frequently spoken cf as fixing agents, but when used in this broad 
and indefinite sense the term frequently leads to confusion 
rather than to enlightenment. In order to eliminate this con- 

447 



448 ELEMENTS OF INDUSTRIAL CHEMISTRY 

fusion as far as possible, we will classify the most important 
compounds coming under this class as follows : 

(1) Mordants: (a) Metallic. (6) Non-metallic, (c) Acid. 

(2) Mordanting assistants. 

(3) Chemical fixing agents. 

(4) Mechanical fixing agents. 

(5) Developing agents. 

(6) Leveling agents. 

(7) Dyeing assistants. 

MORDANTS. Mordants in general may be defined as sub- 
stances capable of uniting with certain dyestuffs to form insoluble 
colored compounds which under the proper conditions may be 
more or less permanently fixed upon textile material. They may 
be subdivided as metallic, non-metallic, and acid mordants. 

Metallic Mordants. Metallic mordants are substances, usually 
metallic oxides or hydroxides, which are capable of uniting with 
certain dyestuffs, known as mordant dyestuffs, to form insoluble 
colored compounds which for the most part are known as color 
lakes. 

Non-metallic Mordants. The only non-metallic mordant of 
importance, and this of only minor importance, is sulphur. Sul- 
phur is sometimes used as a mordant when applying certain basic 
colors, e.g., malachite green upon wool. 

Acid Mordants. Tannic acid and various substances rich in 
this acid, such as sumac, gall nuts, and various bark extracts, 
and less frequently various fatty acids, such as oleic and stearic 
acids, and Turkey red oil, are the only acid mordants of impor- 
tance. Of these acid mordants tannic acid and its related com- 
pounds are the only ones commonly used, and these chiefly in the 
application of the basic colors to cotton material. The acid 
mordants are of minor importance as compared with the metallic 
mordants. 

CHEMICAL FIXING AGENTS. Under the heading of chem- 
ical fixing agents we will include: 

First. Those substances which are instrumental in the fixa- 
tion of various mordants upon textile material by uniting chem- 
ically with such mordants and holding them upon the fiber until 
the proper dyestuffs may be given an opportunity to unite with 
them. Examples: The various antimony compounds used to 
fix tannic acid upon cotton fiber. Various tannin compounds 



DYESTUFFS AND THEIR APPLICATIONS 449 

used to hold iron upon the fiber as the insoluble tannate of iron 
when the latter is to act as a mordant with logwood or other 
mordant dyestuffs. 

Second. Those substances which cause the actual precipita- 
tion of the mordant usually by the double decomposition of the- 
mordanting principle. Example : When cotton material saturated 
with nitrate of iron is passed through a solution of sodium car- 
bonate, the basic carbonate and oxide of iron is precipitated upon 
the fiber, and sufficiently fixed thereon to act as a mordant. 

Mechanical Fixing Agents. These are substances (such 
as albumen) capable of holding pigments, permanently, upon the 
fiber, or certain gums and starches capable of holding dyestuffs 
and other substances upon the fiber a sufficient length of time 
to permit of some desirable reaction taking place. Their action 
is purely mechanical. 

DEVELOPING AGENTS. The term developing agents is applied 
to organic compounds which in combination with some other 
organic compound already deposited upon the fiber will develop 
a colored compound, or if united with a dyestuff already upon the 
fiber will form a new coloring matter possessing a more desirable 
or a faster color. Examples: Beta-naphthol upon the fiber, 
when combined with diazotized para-nitro aniline (developing 
agent) will produce para red. Primuline, a yellow dyestuff, 
when diazotized upon the fiber by treatment with nitrous acid 
and then combined with beta-naphthol (developing agent) pro- 
duces a very bright red coloring matter. 

LEVELING AGENTS. Leveling agents are compounds added 
to the dye-bath in conjunction with certain dyestuffs to assist 
in bringing about the level or even deposition of the latter. Ex- 
ample: Glauber's salt used in conjunction with the direct cotton 
colors. 

DYEING ASSISTANTS. Dyeing assistants are compounds 
which, added to the dye-bath, facilitate the dyeing process and 
are beneficial in one way or another. Examples: Sulphuric acid 
and Glauber's salt in the dyeing of acid colors. 

CLASSIFICATION OF THE DYESTUFFS. The earliest classifica- 
tion of dyestuffs was made by Bancroft, who divided them into 
two classes, substantive and adjective. He designated as substan- 
tive dyestuffs those capable of producing a fully developed color 
upon textile material without the necessary assistance of any 
other combining substance, and as adjective dyestuffs those 
requiring an intermediate combining substance {called a mor- 



450 ELEMENTS OF INDUSTRIAL CHEMISTRY 

dant) satisfactorily to fix and fully develop the color. This 
grouping is still in use, but during recent years the tendency has 
been to use the term direct color, instead of substantive, and 
mordant color instead of adjective. In general the classification 
holds true; but there are instances where dyestuffs are substan- 
tive toward one fiber, but adjective toward another. This is 
well illustrated by the basic colors which will dye wool directly 
but require a mordant upon cotton. 

The classification which divides the dyestuffs according to 
their origin is of broader application. It recognizes three groups 
and is as follows: 

(1) Natural Organic Dyestuffs. Including (a) Vegetable; 

(b) Animal. 

(2) Mineral Dyestuffs. 

(3) Artificial Organic Dyestuffs. 

Though the various subdivisions of this classification, par- 
ticularly of the artificial organic dyestuffs, are numerous and varied 
in the character of the dyestuffs they include, this general classi- 
fication has the advantage of conciseness, and one class does not 
overlap another. 

The natural organic dyestuffs include such coloring matters 
as logwood, indigo, fustic, cutch and cochineal. 

The mineral coloring matters include Prussian blue, chrome 
yellow, iron buff and a number of other inorganic pigments. 

The artificial organic dyestuffs are the most important, and 
this class may be divided into twenty or more important sub- 
classes. They include all of the so-called coal-tar dyes, such as 
magenta, benzo-purpurine, acid violet, tartrazine, and the 
alizarines. 

Natural Organic Dyestuffs. For convenience we shall 
subdivide the natural organic dyestuffs as follows: 

(1) Indigo and related compounds. 

(2) Logwood. 

(3) Natural dyestuffs, producing shades of a red character. 

(4) Natural dyestuffs, producing shades of a yellow to 

brown character. 

Indigo. Indigo blue or indigotin occurs in many plants, 
chiefly those of the genus Indigofera, the Indigofera tinctoria 
yielding the largest quantity. The Indigofera thrive only in 



DYESTUFFS AND THEIR APPLICATIONS 451 

tropical climates, and for several hundred years the cultivation 
of the indigo plant was one of the chief industries of Southern 
Asia, particularly India and Java. The introduction of the 
artificial indigo, however, has dealt a severe blow to the natural 
indigo industry, particularly during the past five years, and the 
synthetic indigo now seems likely to replace entirely the older 
vegetable product. 

The indigo plant is herbaceous in character, grows 3 or 4 ft. 
high, and with a stem about J in. in diameter. 

Indigo blue, or indigotin, as it is known chemically, does not 
exist as such in the plant, but is developed through the indirect 
decomposition of a glucoside known as indican. When the leaves 
and stems are steeped in water and allowed to ferment, a clear 
yellow liquid results which contains the indigo as the soluble 
indigo white. When this liquor is violently agitated, so as to 
expose all parts to the action of the oxygen of the air, the soluble 
indigo white is converted into the insoluble indigo blue. This 
is allowed to settle, pressed into cakes, and when dry is ready for 
the market. 

Indigo Extracts. These are prepared by the action of 
concentrated sulphuric acid upon indigo blue. The resulting 
compounds are the indigotin sulpho acids, which are freely 
soluble in water, and may be easily applied to wool in an acid 
bath. They dye wool a brighter blue than ordinary indigo, but 
unfortunately the dyeings produced are extremely fugitive to 
light, whereas vat indigo on wool produces one of the fastest 
blues known. The use of the former is very much restricted for 
this reason. The indigo extracts are of no value for cotton dye- 
ing. 

Logwood. Logwood is the product of a large and rapidly 
growing tree known botanically as the Hcematoxylin campechi- 
anum. It is a native of Central America and the adjacent islands, 
Jamaica being one of the chief centers of the logwood industry. 
Raw logwood, as the name implies, comes in the form of rough 
logs, which are ground or rasped into small chips. It may be 
used in this latter form after it has been properly aged, bur dur- 
ing recent years it has been more frequently put upon the market 
in the more concentrated form of an extract. 

Logwood is in every sense of the word a mordant dyestuff, 
a metallic mordant being required to satisfactorily fix the dye- 
stuff upon any textile fiber. During the dyeing process the 
hsematein of the logwood unites with the mordant to form an 



452 ELEMENTS OF INDUSTRIAL CHEMISTRY 

insoluble metallic organic compound or color lake, which becomes 
fixed upon the fiber. 

Logwood is extensively used for the production of blacks upon 
silk. Iron mordants are depended upon almost entirely for this 
purpose and tin mordants occasionally. The process usually 
consists in alternately treating the silk with some tannin material, 
and an iron or a tin compound until the silk is thoroughly filled 
with the metallic tannate. The silk thus mordanted is then dyed 
in a logwood bath. By using tin compounds in conjunction with 
acetate of iron it is possible to weight black dyed silk as much 
as 300 per cent of its original weight. 

Soluble Red Woods. Brazil wood, peach wood, Japan wood, 
and Lima wood are the principal soluble red woods. They 
are all mordant colors, and may be applied to mordanted cotton 
or wool by boiling in a plain bath of the extracted color. 

Insoluble Red Woods. These include barwood, Saunders 
wood, and camwood. On account of the insolubility of the 
coloring matters which they contain, the ground or rasped chips 
of wood must be added directly to the dye-bath. They are all 
mordant colors. The red woods have been replaced by coal- 
tar colors, which give more permanent and clearer dyeings at a 
lower cost. 

Madder. Madder root, which was known to the ancients, 
was for many hundreds of years the most, important of the red 
natural coloring matters, and was used chiefly in conjunction 
with Turkey reds. The active coloring principle of madder is 
alizarine C14H8O2, and the discovery in 1868 by Graebe and Lieber- 
mann that alizarine could be cheaply made from coal-tar deriva- 
tives, soon led to the abandonment of madder as a coloring matter 
except in the Oriental countries where it is native. 

Cochineal. Cochineal is a red mordant coloring matter 
obtained from the dried body of an insect which is a native of 
Mexico and Central America. In the past, cochineal was exten- 
sively used for the production of scarlets and crimsons on wool 
in conjunction with tin and aluminium mordants. Like most 
of the other natural colors, cochineal has been superseded by the 
artificial dyestuffs. 

Natural Dyestuffs of a Yellow to Brown Color. The yellow 
natural dyestuffs include a number of vegetable dyestuffs which 
vary between yellow and brown. Fustic, quercitron bark, 
Persian berries, turmeric, weld, and cutch are the most im- 
portant. 



DYESTUFFS AND THEIR APPLICATIONS 453 

Fustic or Cuba Wood. Fustic or Cuba wood is the most im- 
portant of the yellow dyewoocls and is still used to some extent in 
wool dyeing chiefly in combination with logwood. It is a 
mordant dyestuff being used with chromium and aluminium 
mordants. It is sold in the form of ground wood, but more 
frequently as an extract. 

Quercitron Bark. Quercitron bark is obtained from the 
bark of a species of oak which grows in the Middle and Southern 
States. It is a mordant color and gives brighter yellows than 
fustic. Its use is limited at the present time. 

Persian Berries. Persian berries is the name applied to 
the berries of the buckthorn. In the extract form it is used to 
a limited extent in calico printing. 

Turmeric. Turmeric is the ground root of a plant which 
grows in Asia. It dyes cotton, wool, and silk bright shades of 
yellow which are extermely fugitive to light and washing. 

Cutch or Gambia. Cutch or gambia, a coloring matter rich 
in tannin, is extracted from the nuts and tender portions of 
various forms of acacia trees growing chiefly in India. It is used 
chiefly for the production of browns upon cotton, also as a tannin 
material in silk dyeing. 

MINERAL DYESTUFFS. The mineral dyestuffs as a class are 
of minor importance in the textile industry. Various mineral 
pigments are sometimes used in calico printing, but in the actual 
dyeing process the only mineral dyes of any importance are 
Prussian blue, chrome yellow, chrome green, iron buff, and 
khaki. 

Prussian Blue. Prussian blue may be produced upon tex- 
tile material by one of two methods. The first consists of mor- 
danting the material with iron oxide, and then boiling in a solu- 
tion of potassium ferrocyanide. The second method makes use 
of the fact that both the ferro and ferricyanides of potassium 
decompose when boiled in an acid solution and from such a boil- 
ing solution Prussian blue is absorbed by textile material. The 
first process is used chiefly with cotton, while the second is better 
adapted to wool dyeing. 

Chrome Yellow. Chrome yellow is the yellow lead chromate 
which may be precipitated upon the fiber by alternate treat- 
ments with solutions of some soluble lead salt and a chromate. 

Chrome Green. Chrome green is a basic oxide of chromium 
precipitated upon the fiber by the reaction of some soluble chro- 
mium salt with an alkali. 



454 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Iron Buff. Iron buff is a ferric oxide precipitated upon 
the fiber by the reaction of some soluble iron salt with an alkali. 

Khaki. Khaki is a yellowish-drab color produced by the 
precipitation upon the fiber of a combination of ferric oxide and 
basic chromium oxide. Khaki when properly dyed produces an 
extremely fast color. 

Artificial Organic Dyestuffs. The natural dyestuffs 
were depended upon almost wholly until the discovery of mauve 
by Perkin in 1856. Mauve was the first of the so-called coal- 
tar dyes, or better artificial organic dyestuffs. Its discovery was 
followed by that of many similar dyestuffs, and a new era soon 
began in the textile coloring industry. To-day several hundred 
entirely different dyestuffs of this class are at the disposal of the 
textile colorist,and from them we can select dyes which will answer 
almost every requirement of shade and fastness. 

Classification of the Artificial Organic Dyestuffs. The arti- 
ficial organic dyestuffs may be classified according to their 
chemical derivation, their composition, or in respect to the 
characteristic color-forming groups which they contain. While 
these classifications prove very satisfactory for the color-manu- 
facturing chemist, they prove of little or no value to the practical 
textile colorist. Another classification which groups them 
according to their action toward the various textile fibers is by 
far the most practical and valuable for the student of textile 
coloring, and will be followed. It recognizes ten classes of color- 
ing matters: 

(1) Basic colors. 

(2) Phthalic anhydride colors. 

(3) Acid colors. 

(4) Direct cotton colors. 

(5) Sulphur colors. 

(6) Mordant colors. 

(7) Mordant acid colors. 

(8) Insoluble azo colors. Produced directly upon the fiber. 

(9) Reducible vat, colors. 
(10) Miscellaneous colors. 

Basic Colors. Chemically the basic dyestuffs belong to 
the class of compounds known as substituted ammonias or 
amines. Like ammonia they are basic in character and hence 
the name. 



DYESTUFFS AND THEIE APPLICATIONS 455 

The basic colors have a direct affinity for wool and silk, but 
no direct affinity for cotton, and can only be applied to the latter 
fiber in conjunction with some acid mordant, usually tannic acid. 

The basic colors are characterized by their great brilliancy 
and high coloring power. Their fastness to light is by no 
means satisfactory, but their fastness to washing in most cases 
is very good. 

The Phthalic Anhydride Colors. The phthalic anhydride 
colors are so called because they are directly related to this 
compound. They included the eosines and rhodamines, and are 
extensively used for the production of bright pinks, particularly 
in silk dyeing, and less frequently in wool dyeing. They are not 
used to any great extent in cotton dyeing, although sometimes 
used in cotton printing. 

The phthalic anhydride colors are characterized by their re- 
markable brilliancy. 

Acid Colors. The acid colors are so called on account of 
their acid character, and furthermore because they dye wool so 
readily in an acid bath. They are of great importance in wool 
dyeing, about 75 per cent of all wool dyeing being accomplished 
at the present time by their use. The acid colors are also exten- 
sively used in silk dyeing, but are of no importance in cotton 
dyeing. 

From a chemical point of view the acid colors may be sub- 
divided according to their composition into three classes: (1) 
Those which are nitro compounds, i.e., those containing the nitro 
or NO2 group. (2) The sulphonated basic colors, i.e., those made 
by treating basic colors with concentrated sulphuric acid, and 
thereby introducing the sulphonic acid or HSO3 group. (3) 
Those which are azo colors, i.e., those containing the azo or 
— N = N— group. The dyestuffs of the third group are the most 
numerous and most valuable of the acid colors. 

Direct Cotton Colors. The direct cotton colors, as their class 
name indicates, have a direct affinity for cotton. All vege- 
table fibers readily absorb the direct cotton colors from their 
simple water solution, but for practical results it is advisable to 
make certain other additions to the dye bath. The direct cotton 
colors also dye the animal fibers directly, but in most cases acid 
colors are preferred. The direct cotton colors having a direct 
affinity for both animal and vegetable fibers find extensive appli- 
cation in the dyeing of union material composed of cotton and 
wool, or cotton and silk. 



456 ELEMENTS OF INDUSTEIAL CHEMISTRY 

SULPHUR COLORS. The sulphur or sulphide colors, as they 
are frequently called, are in many respects similar to the direct 
cotton colors, but differ so entirely in many other respects that 
they are grouped by themselves. In recent years they have 
become an important factor in cotton dyeing, on account of the 
fastness of the dyeings they produce, and they are now exten- 
sively used for the production of fast blacks, blues, browns, and 
compound shades upon cotton. 

They are called sulphur colors for three reasons: In the first 
place, sulphur is a constituent of all of the dyestuffs of this class; 
sulphur and sodium sulphide are largely used in their manu- 
facture; and finally, sodium sulphide is almost without exception 
a necessary constituent of the dye-bath during their applica- 
tion. 

Artificial Mordant Colors. The true mordant dyestuffs 

included under this heading cannot be permanently fixed upon 
cotton, wool or silk, except in conjunction with some metallic 
mordant. They are usually fixed upon the textile material as 
insoluble oxides or hydroxides of chromium, aluminium, and iron 
and less frequently tin and copper. During the dyeing process 
which follows the mordanting, the mordant dyestuffs, which con- 
tain either hydroxyl (OH) or carboxyl (COOH) groups in their 
composition, react with the mordants in much the same manner 
as acids react with bases, the result being the formation of insoluble 
metallic organic compounds of a salt-like character which are 
known as color lakes. This reaction takes place in situ and the 
color lake is thus fixed upon and within the fiber. 

MORDANT ACID COLORS. The dyestuffs of the group known 
as the mordant acid colors are intermediate in general character 
between the acid dyestuffs and the mordant dyestuffs. They 
resemble acid colors in a general way, dyeing wool directly in an 
acid bath, but at the same time resemble the mordant colors, in 
that they may be applied to advantage in conjunction with 
metallic mordants. 

INSOLUBLE AZO COLORS. A number of coloring matters of 
the azo type exist, the insolubility of which renders the mnon- 
applicable by any of the methods already described. Fortu- 
nately the nature of the process of their formation is such that 
they may be produced directly upon the fiber. Many insoluble 
azo colors may be produced, but only two, the so-called para- 
nitr aniline, and alpha-naphthylamine reds have proved to be of 
practical value. These have been extensively used upon cotton 



DYESTUFFS AND THEIR APPLICATIONS 457 

during the past twenty years, the former having replaced Turkey- 
red to a great extent. 

The dyestuffs of this class are also known as developed colors, 
because they are developed during the process of application, 
also as ice colors, because ice is used to attain a low temperature 
during their formation. 

The formation of the insoluble azo colors depends upon the 
fact that certain diazotized amino compounds produce insoluble 
coloring matters when brought into contact with certain naphthols 
or phenolic bodies. Para-nitraniline red, the most important ex- 
ample, is produced by padding cotton cloth with sodium beta- 
naphtholate, prepared by dissolving beta-naphthol in caustic 
soda solution, and then passing the cloth thus prepared through 
a bath containing a cold solution of diazotized para-nitraniline, 
the latter ,being prepared by the action of nitrous acid upon para- 
nitraniline hydrochloride. As soon as the cloth prepared as above 
comes in contact with the para-nitraniline solution, a bright red 
develops which possesses excellent fastness to light and washing. 
If diazotized alphanaphthylamine is substituted for the para- 
nitraniline a claret red color is produced of corresponding fastness. 

The insoluble azo colors are not applicable to wool, owing to 
the fact that a strong caustic soda solution must be used in dis- 
solving the naphthol, which would act injuriously upon the fiber. 

REDUCTION VAT COLORS. The reduction vat colors have 
come into great prominence during recent years owing to their 
great resistance to practically all of the color-destroying agencies, 
particularly light and washing. The chemistry of their appli- 
cation is the same as that of indigo, in fact indigo is a reduction 
vat color in every sense of the word. As a class these colors are 
insoluble in water, but when strongly reduced in an alkaline 
bath they form soluble, usually colorless or almost colorless, 
reduction compounds, which are easily absorbed by the fiber. 
Upon subsequent oxidation the reduced compounds pass back 
to the original insoluble dyestuff which becomes fixed upon the 
fiber. 

From the point of view of composition, the reduction vat 
colors may be divided into two classes : first, those directly related 
to indigo; secondly, those related to anthracene. The former may 
in most cases be applied to both cotton and wool, but the latter 
only to cotton. 

Another important group of coloring matters of recent develop- 
ment are the so-called sulphurized vat dyes. In their properties, 



458 ELEMENTS OF INDUSTRIAL CHEMISTRY 

they may be considered as intermediate between the vat colors 
and the sulphur colors. But little is known in regard to their 
composition. The dye-stuffs known as hydron colors belong to 
this group. 

The coloring power of the reduction vat colors is weak and 
a comparatively large amount must be used in must cases. 

ANILINE BLACK. Aniline black is usually classified as one 
of the miscellaneous colors, for it does not belong to any of the 
other groups. It is in reality an insoluble black pigment pro- 
duced by the oxidation of aniline. 

When aniline is oxidized, three consecutive products are 
formed: (1) Emeraldine, a greenish-colored salt insoluble in 
water; (2) niqr aniline, formed by the oxidation of emeraldine, 
and (3) aniline black proper, or ungreenable black, as it is some- 
times called, which is formed by a still further oxidation of ni- 
graniline. The composition of the final product is not definitely 
known. 

Aniline black is extensively used in calico printing and the 
dyeing of hosiery, but cannot be used successfully in wool dyeing. 

In general, aniline black is applied by preparing or printing 
the material with a mixture of aniline hydrochloride and certain 
oxidizing agents and oxygen carriers, such as potassium chlorate, 
potassium ferrocyanide, copper sulphide, or vanadium salts, and 
subsequently drying and aging it by passing through an aging 
chamber. 

Aniline black is extremely fast to light, bleaching and washing. 



CHAPTER XXV 
THE PAPER INDUSTRY 

RAW MATERIAL. At the present time the manufacture 
of paper has two principal bases of supply. One of these is rags, 
the other is wood. Out of rags is made the highest grades of paper. 

RAG PAPER. All linen and cotton rags can be converted into 
different grades of paper according to the kind and color of the 
rags. Great care is used in sorting rags before delivery to the 
paper mill so as to get a uniform kind of rags of the same color. 
Buttons, pieces of metal, sticks, stones, rubber and all foreign 
articles must be removed. 

The treatment of rags in the mill is as follows: The rags are 
delivered at the mill in strap iron bound bales about 3 ft. square 
and 5 ft. long. Often several hundred tons and sometimes two 
or three thousand tons are kept on hand. 

The rags in bales as demanded for use are taken to the rag- 
room, where the bales are opened by women, who make the final 
sorting, inspection and cutting. The finest sort goes into the 
best of writing paper. From this high standard to the pasteboard 
and cheapest wrappers are many grades supplied by the different 
quality of rags. 

A scythe-shaped knife is fastened in a vertical position to a 
table, by which the operator cuts the rags fine or coarse, and 
also separates all foreign matter that may be seen. At this 
stage the rags pass to the mechanical rag cutters, that cut them 
up into small pieces so that the duster, through which they next 
pass, can remove much of the loose dirt. These machines dust 
out oftentimes five per cent or more of the weight of the rags 
and also open them up so that the chemicals in the votaries or 
cookers into which they are placed can better penetrate and 
act upon them. 

RAG BOILERS. Rag boilers are of several types. The 
stationary upright cylinders are provided with a manhole on top 
for filling, the cover to which is bolted on or held up by yoke and 
bolts. By the opening of a valve, at the bottom, the contents 

459 



460 ELEMENTS OF INDUSTRIAL CHEMISTRY 

are blown out, due to the pressure (generally about 30 lbs.) main- 
tained during the cooking. Steam for cooking is admitted at 
the bottom and the liquor circulated by an outside pump. 

Rotaries are horizontal cylindrical-shaped steel tanks 10 to 
20 ft. long and 6 to 8 ft. in diameter with heads riveted on each 
end, each head having a journal upon which it rests and is turned 
during the cooking process. Hence the name " rotary." 
Through one of these journals steam enters for cooking. The 
rotary may have one or two manholes with covers affixed, as in 
the upright, for filling in the stock. During the filling men go 
into, the rotaries and pack the stock into the ends so as to 
get in enough properly to fill the boiler. 

RAG BOILING. The chemicals, a certain number of gallons 
of a solution of caustic soda or soda ash and caustic lime, or a 
milk of lime made by slacking and boiling caustic lime in water, 
are added. In all cases where lime is used it should be strained 
in order to remove unslacked parts before being passed into the 
cooker. When the liquor is all in, the covers are adjusted and the 
steam turned on. The pressure generated (generally 15 to 30 
lbs.) and the chemicals reduce the foreign matters, such as grease 
loading materials, dirt, etc., and open up the fibers so that in the 
next operation of beating they can be perfectly cleaned and 
reduced to the desired length. Some manufacturers blow off 
the cooking liquor of the rotaries and run in fresh water to wash 
the stock in the rotaries, but generally the stock is dumped as 
soon as cooked and pressure lowered by removing the covers of the 
manholes. Sometimes the stock is allowed to stay in piles for 
several days in order to ripen after it is cooked. It is eventually 
taken to the beater engine. 

BEATER ENGINE. This is a Holland invention, sometimes 
called a Hollander, for washing, beating and reducing the fibers 
of the paper stock. The beater engine is an oval-shaped tub 
about 20 ft. long by about 3 ft. high by about 8 ft. wide. They 
are made of wood or iron shell with floor of wood or cement and 
are often lined throughout with copper. A partition, the " mid- 
feather," extends as far as the rectangular part of the body. A 
beater roll 4 to 5 ft. in diameter with heavy knives parallel to 
the shaft is fitted into its face and is suspended in one of the 
divisions, nearly filling it. This roll which consists of a number 
of steel plates standing on edges bolted together, can be raised or 
lowered nearly onto the bedplate by the beater man. The rais- 
ing or lowering of the roll determines the ultimate length and in a 



THE PAPER INDUSTRY 461 

great measure the condition of the fiber when finished. Between 
the roll and the bedplate all of the stock must pass. The cir- 
culation of the stock around the beater is given by the roll, which 
acts as a paddle wheel. While the stock is washing, clean water 
is added at one side of the roll. This is thoroughly mixed with 
the stock as it passes under the roll and on the other side a re- 
volving drum washer with a fine wire on its face is pressed into the 
pulp. The dirty water is thereby removed from the stock. 

This process is continued until the stock is clean, during which 
time the roll or bedplate is raised so that but little cutting 
is done. At this point the stock is often bleached in the 
beater by means of a solution of calcium hypochlorate, gen- 
erally called bleach. This bleach is made by mixing common 
bleaching powder with water and allowing the lime sludge to 
settle out, Only a clear bleach solution testing about 4 to 5° 
Be. should be used. When bleached to the requisite color the 
stock is either dumped to a drainer to finish the bleaching or to 
be thoroughly washed; or it is washed in the beater by the addi- 
tion of more water and oftentimes some antichlor is added to 
hasten the killing of the bleach. Washing is kept up until these 
chemicals are washed out, then the roll is gradually lowered and 
the pulp is reduced to the proper condition. When nearly 
" ready " the required color, if any, is put into the beater, then 
size, if it is to be engine sized, is added. The size is made with 
soda ash about one part, rosin about four parts, dissolved and 
thoroughly boiled in water, well diluted, and then alum intro- 
duced to set the sizing onto the fibers. The stock is run in the 
beaters a short time and then dropped into the stuff chest, where 
it is kept well stirred until it is wanted on the paper machine. 

JORDAN ENGINE. In its passage to the machine the stock 
is generally run through a Jordan engine, that reduces its fibers 
to final readiness for the sheet of paper. This engine is a cone- 
shaped plug, about 4 ft. long, made up of steel bars and hard wood, 
that fits into an iron sleeve or hollow cone made to receive it, 
being lined with a filling similar to that on the plug. Through 
this Jordan all the stock passes, and by the closeness of the plug 
to the sleeve the stock is finally reduced to the proper condition 
for the machine. It is then sent to the machine stuff chest, from 
which it is pumped to the flow box, where the right quantity of 
water is added to make it flow properly through the screens. 
The screens remove all particles too coarse to go into a sheet of 
paper. The stock passing through the slots, which are generally 



462 ELEMENTS OF INDUSTRIAL CHEMISTRY 

about j 1 ^ of an inch in width, drop to the apron and then onto the 
wire of the machine, if it is a Fourdrinier. 

FOURDRINIER MACHINE. Paper may be made on the Four- 
drinier type, with a wire at the wet end upon which to form the 
sheet; the Harper type with felt and wire, or the cylinder 
machines; the difference being principally at the wet end, where 
the paper is formed. The drying ends are as a rule similar. 
The cylinder machines have from one to six vats, with cylinders 
in each, making a sheet of paper that is laid on the next in front, 
so that when finally they go to the felt it is a built-up sheet of 
one/ two or more sheets of paper according to the number of vats 
used to make it. When dry the whole sheet can be split up into 
the different sheets it is made out of. Much of the heaviest paper 
is made on this machine, which, however, is not a fast running one. 

The paper machine in general use for news and many other 
kinds of paper as well as rag is the " Fourdrinier/' which, while 
it does not make as thick a sheet as the others, can make light as 
well as medium weights easier, change quicker, run faster and 
produce a good tonnage. 

The wire of the Fourdrinier machine is made endless, i.e., 
its ends are woven together so that it will pass around the rolls 
like an endless belt and it is stretched out like a horizontal oblong 
table. It is supported by a series of brass rolls at intervals, as 
demanded by the work to be done. Its width varies from 36 
to 200 inches, the length varying in due proportion. A rubber 
deckel strap about 2 in. square runs at each side to hold the pulp 
and water on the wire, also by the moving in or out of the deckel 
straps, the width of the sheet can be changed to meet the demand. 
The proportions of these parts are such that the sheet of paper 
can remain on the wire long enough to get rid of its superfluous 
water by draining through the wire, by squeezing out water in 
passing between presses, couch rolls, over suction boxes, etc. 

This wire is one of the most important and costly parts of the 
machine. Its condition means the appearance of the sheet of 
paper. Great care is taken to keep knots of stock, stray pieces of 
iron or wood or any hard foreign matter, off the wire, as a puncture, 
a tear, or any damage to it means a shut down of the machine 
until it is made as nearly perfect as possible. The wire must 
be kept clean so that the water can freely pass through it any- 
where. Should it plug up, the stock is shut off and the plugs 
cleaned off, as a thin spot in the sheet of paper would show each 
time the spotted section carried the sheet along. The sewing 



THE PAPER INDUSTRY 463 

of the wire is a delicate piece of work and must be done so as to 
match the weave of the wire, and not leave a mark on the sheet 
of paper. The sheet of paper is fully formed on the wire. While 
in the forming state the fibers of the sheet are felted together by 
the shaking motion, which, although a very short stroke, in itself 
seems to make a felting of fibers that distinguish a tough Four- 
drinier-made sheet from a cylinder-made sheet, wherein the 
fibers all run in about the same direction. There is also often a 
dandy roll that places a name or figure in the paper, such as one 
can see when it is held up to the light. This stamps the name 
into the sheet of paper while it is wet and is sometimes called a 
" watermark." With all this manipulation two-thirds of the 
weight of the sheet of paper before going to the steam dryers is 
water. 

At the end of the wet end nearest the dryers is the last press 
through which the wire passes. The sheet of paper will now be 
well formed and leave the wire and stick to the surface of the top 
roll. A sharp-edged scraper, called a doctor, prevents the sheet 
from passing entirely around the press. At this point the back 
tender strips off the roll a 2- or 4-in. wide piece and carries it 
across the gap to the first dryer. As the speed of the machine 
is from 60 to 600 ft. a minute for this sheet of paper much dex- 
terity is required at this place. A man stands at the press roll, 
gradually working the strip that he started tearing off at the end 
of the press, across to the other end, making a diagonally cut 
sheet that eventually grows from the 2-in. wide strip to one the 
full width of the sheet of paper. 

The dryers are steam-heated, hollow cast-iron cylinders 3 or 
4 ft. or more in diameter with a width of from 36 to 200 ins., as 
the machine may be built, placed one above the other. A strong 
cotton duck dryer felt is held up to the bottom dryers by rollers 
in order to hold the wet sheet up to the hot surface. The sheet 
of paper goes about two-thirds around the bottom dryer, up and 
over to the top dryer, where it comes into contact with as much 
of that surface as it can and drops down to the second bottom 
dryer. This is repeated until it has come into contact with all 
of the dryers of the machine (ten or sixty, according to the make) , 
when it leaves the machine and is passed by hand to the reel 
or up to the top pair and down between the others of a stack 
of calender rolls, between which it is run to smooth or polish the 
surface of the sheet. From the calender it passes to the reels; 
from the reels through the slitters that cut the sheet into the 



464 ELEMENTS OF INDUSTEIAL CHEMISTRY 

width desired and then to the winders, where it is wound up into 
rolls. When demanded these rolls are taken to an apparatus 
called a supercalender, where the surface of the sheet is further 
polished by running between heavy steel rolls, and then it goes 
to the cutters, where it is cut up into any size of sheets demanded. 

WOOD PAPER. From the different varieties of spruce, pine, 
fir, hemlock, poplar, and other woods, we obtain practically 
all of our newspaper, nearly all even of our book paper, and 
a large portion of our writing papers. 

On the arrival of the wood at the mill, if it is to be chemically 
treated, it is generally piled up so that it may dry; it is allowed 
to thus season in the pile for one, two or perhaps three years. 
This seasoned wood loses much of its sap and water and requires 
less chemicals to convert it than the green wood directly from 
the forest. For the mechanical pulp a fresh green wood produces 
better fiber and is easier ground up than the dry seasoned wood. 
For any of the treatments the bark must be removed, which is 
done by a machine called a barker or by the hand draw-shave. 

In the wood paper industry the principal methods of treating 
wood to produce fiber are by grinding, producing ground wood or 
mechanical fiber, and cooking by either the caustic soda or the 
sulphite process. 

MECHANICAL PROCESS. The mechanical process consists 
of placing blocks of wood about 18 ins. long in apertures, called 
pockets, of a heavy cast-iron frame that encases a large grind- 
stone. This grindstone revolves at about 200 revolutions per 
minute, a stream of water plays against its face to keep the wood 
from burning, as it is pressed against the face by hydraulic pres- 
sure of about 30 pounds. The result of this is the reduction 
of the wood to a fine pulpy mass, which is called mechanical pulp 
or ground wood. This is floated by water on to a coarse screen, 
by which the pieces of wood that have not been ground up are 
removed. The pulp goes to a fine screen, through which the 
mechanical pulp, that is, the right kind to go into the making of 
newspaper or other papers, passes. This pulp now goes to the 
beaters in the beater room to be mixed with sulphite pulp or other 
stock, according to the grade of paper it is desired to manufacture, 
and from the beaters goes to the paper machine, as described 
under Rag Paper, or to a wet machine, which is an apparatus 
for getting the pulp into a state dry enough to handle. The Wet 
Machine is a wooden vat 6 ft. wide, 8 ft. long and 5 ft. deep, 
into which the mixture of water and ground wood is pumped. A 



THE PAPER INDUSTRY 465 

bronze cylinder about 3 ft. in diameter by 6 ft. long, covered with 
a brass wire net of 60-mesh, is immersed in the mixture in such a 
manner that the water passes through the meshes of the wire, 
leaving the pulp sticking to its surface. A coarse woolen blanket, 
called a felt, is pressed against the cylinder mold by a heavy 
couch roll. The blanket automatically picks off the pulp from the 
face of the cylinder, carries it along on its surface over a suction 
box and between heavy press rolls, that extract quantities of 
water from it and leave it with from 35 to 50 per cent of pulp. 
One of the rolls of the press is of hard maple wood, which picks 
the pulp from the blanket when it comes in contact with it. 
As the press roll revolves, the pulp is continuously added to 
it from the blanket until the sheet is thick enough, in the 
judgment of the press tender; who then with a sharp pointed 
wooden pin cuts it off by passing the point under the sheet 
close to the wood roll, across the face of the roll. The sheet of 
pulp is rolled off on a table, folded up, weighed and is then ready 
for shipment or storage. 

SODA PROCESS. The caustic soda liquors are made by 
dissolving soda ash in water, and to this solution adding about 
55 to 60 per cent of freshly burnt pure quicklime, bringing 
the mass to a boil, mixing it thoroughly by stirring, then al- 
lowing the calcium carbonate produced, to settle to the bottom. 
The clear caustic liquor is siphoned off, and the lime sludge 
washed two or three times with water to remove as much of the 
caustic soda as possible. 

Poplar wood and kindred species are principally used in the 
soda process, as they yield easiest to this treatment, requiring a 
smaller amount of caustic soda for reduction than do other woods. 
The well-seasoned wood is brought to the mill where it is in- 
spected and all bark, dirt and black knots removed, as these 
make objectionable color and dirt in the pulp and paper. These 
sticks of wood are then taken to a machine called a chipper, 
which slices off the wood into slices similar to a sliced onion 
that break into chips about f inch long by 1 inch by ^ inch. 
The thickness of these chips will generally be the annual growth 
of the wood. The chips are screened to remove the sawdust, 
knots and coarse pieces; the latter passed through a rechipper, to 
reduce to the proper size. The chips are stored in large bins over 
the digesters, into which they are run by gravity. The digesters for 
the soda process are made of steel 1 inch thick and are some- 
times 50 feet high by 10 feet in diameter. They are filled full 



466 ELEMENTS OF INDUSTRIAL CHEMISTRY 

of chips and then a certain amount of the caustic soda solution 
of a density of 8 to 10° Be. is added, according to the character 
of the wood to be cooked. When filled, the cover of the 
digester is bolted down and steam is turned on through the 
bottom. In the soda digesters there is a false bottom, which 
allows the hot liquor to pass down through it. There is gener- 
ally an ejector under this false bottom, through which steam 
is passed, which lifts the cooking liquor at the bottom, 
carries it through a pipe to the top of the digester and sprinkles 
it over the chips, thus making a continuous circulation, that 
produces thorough cooking. The cooking of the chips dissolves 
everything except the cellulose fibers. When completely cooked, 
the contents of the digester will be found to have shrunk one- 
quarter to a third of its bulk, but at this point the chips retain 
their original form. 

A cooking pressure of 90 pounds is maintained in the digest- 
ers for from 8 to 10 hours, with frequent opening of the relief 
valve at the top to draw off gas, when a sample of pulp is drawn 
to ascertain if the wood is properly cooked. When the operation 
is completed a valve of 6 or 8 inches diameter at the lower 
part of the digesters is opened and the entire mass is violently 
blown out of the digester into a suitable receiving tank 
This violent action and the impact of its contents serves to 
shatter or destroy the original form of the chips and a pulpy mass 
of fiber results. The liquor which has been employed for the 
reduction, now called black liquor, is carefully drawn off, by 
repeated washing with weaker liquors or water in the wash tanks 
evaporated to a consistence of 35 to 40° Be. by means of some 
suitable evaporator, generally a yaryan, for evaporation. It 
goes now to a rotary furnace, where it is further dried, and tne 
tar and other wood products are burned up, leaving the soda 
mixed with charcoal. This black mass is called " black ash " 
and is put into the tank. The soda which it contains is leached 
out and is used over again with addition of fresh soda ash and 
caustic lime. A recovery of from 85 to 90 per cent of the original 
soda ash used is generally obtained and this materially reduces 
the cost of chemicals employed. The profits of the mill are 
largely dependent upon this part of the manufacture. All soda 
fibers when cooked and washed clean from the cooking liquors 
are somewhat colored, and if a white paper is desired they must 
be bleached to the desired whiteness. If a colored paper is 
demanded, the color desired can be made in many cases without 



THE PAPEE INDUSTRY 467 

recourse to bleaching. The pulp when washed clean is passed 
through screens, which remove from it uncooked wood and coarse 
matters, and either goes to the beaters, where it is mixed with 
other fibers in the beaters to make the desired grade of paper, 
or it is bleached if required and then pumped to the wet machines 
previously described, to put into condition for handling in ship- 
ment or storage. Soda fiber is a soft stock and is largely used 
in the better magazine, book and writing-paper grades. It is of 
a soft, spongy-like feeling to the fingers and is a quality desired in 
paper used for books. It is a fiber that does not deteriorate by 
time, as the chemicals that have produced it do not have a rotting 
effect upon it unless it is overbleached. Its selling price when 
bleached is about $45 per ton. 

SULPHITE PROCESS. Sulphite fiber, perfected in 1885, is 
made by treating spruce and similar woods with sulphurous acid, 
combined with lime and magnesia, in special digesters made 
with lining to withstand the action of the corrosive acids. The 
largest amounts of chemical fiber is produced by this process. 
The spruce, fir and hemlock, from which most of this pulp is made, 
is piled, dried, cleaned, chipped and screened and conveyed into 
the chip bins above the digesters practically in the same manner 
as for the soda process. The digesters for this process are built 
of heavy 1-in. steel and are very large, being often 50 ft. high by 
18 ft. in diameter, made to contain 20 to 30 cords of wood at a 
charge. 

On the inside of these digesters there is generally placed a 
protective lining of lead fastened to the shell of the digester or 
a backing of about 6 ins. of Portland cement plastered onto every 
part of the inside steel shell of the digester; then up against this 
cement is laid an inside facing of vitrefied acid proof brick laid up 
in a cement made of Portland cement, litharge and glycerine, be- 
cause the acid, if it came in contact with the steel would attack it. 

These digesters are loaded full to the top with chips and 
bisulphite liquors run into the digester to within about 3 ft. of the 
top. This bisulphite acid or cooking acid is made by burning 
sulphur in specially built furnaces. In some of the countries of 
Europe pyrites, on account of its cheapness, is used instead of 
sulphur, but it has not been found profitable to use pyrites in this 
country. The gas first goes through cast-iron pipes to cool 
it, then it enters lead pipes immersed in cold water fur- 
ther to reduce the temperature. It next passes successively 
through three or four wooden tanks containing a mixture of 



468 ELEMENTS OF INDUSTRIAL CHEMISTRY 

milk of lime that absorbs the gas as it comes in contact 
with it. The milk of lime best suited for this purpose is made 
from dolomite, often carrying 45 per cent of magnesia. The gas 
enters the tank at the bottom, leaving at the top, mixing with 
the milk of lime in successive tanks till the sulphur dioxide is 
finally all absorbed and the residual air passes out of the heavy 
vacuum pumps that pull the gas from the furnace to them. 

The digester with its acid is sealed and relief pipes con- 
nected to the top cover. The digester has no false bottom 
and the steam is applied directly through its cone-shaped 
base. The circulation of this digester depends on the passage of 
the steam into the bottom, working its way up through the mass 
of chips and liquor, causing the sulphur dioxide to break loose 
from its combination with the lime and magnesia and the re- 
sultant gas is relieved through the escape valves and pipes on the 
top of the cover. 

In the cooking of the sulphite pulp in the digester the mass 
of chips shrinks as it does in the soda process. During this process 
a pressure of 90 pounds is maintained in the digester and the 
temperatures run as high as 350° F. The quick cooks are made in 
six to ten hours, the slow cooks are steamed from thirty-six to 
seventy-two hours. The slow cook produces the strongest fibers 
that we have and it uses a weaker strength of chemicals than the 
quick cooks. The vertical digesters are discharged in a similar 
manner as with the soda ones. The pulp on being blown out 
strikes a bronze plate called a target and is almost white. The 
cooking liquor is at once washed out of the pulp by flooding the 
tank into which it is blown with fresh clean water. The tank has 
a perforated bottom connected to the sewer with a valve so as 
to control it easily. The water used for this washing, strange to 
say, must be pure and more care taken to insure its cleanliness 
than with the water we generally drink. This waste liquor has 
been experimented on extensively, but up to the present time it 
is found to be of value only in tanning and as a binder for slack 
coal in making briquets for fuel. The cooking acid must be 
thoroughly washed out of the sulphite pulp, because if it is not 
the color of the pulp will turn pink or darken to a light gray slate 
color. After washing, the stock is passed through screens with 
mesh not finer than ^ in., through which the fiber itself passes, 
leaving behind the knots and uncooked pieces and coarse stuff, 
which are sent to the scrap heap to be ground up. When sul- 
phite pulp is to be shipped to another mill or piled up and stored it 



THE PAPER INDUSTRY 469 

is run over the wet machine which has been previously described. 
If there is a newspaper mill connected with these plants, the 
ground wood and the sulphite are each pumped to it and mixed 
together in beater engines. For the common newspapers of 
to-day 75 per cent of ground wood pulp is mixed with about 25 
per cent of sulphite pulp, some size and alum is added and a little 
pink and blue aniline to give it the required white tint. After 
beating in the engine from a quarter to a half hour, the stock is 
dropped into a stock chest, from whence it is pumped to a Jordan 
engine, which shortens the fiber to the proper length for the 
sheet of paper. From the Jordan engine it goes to the stock chest 
that supplies the paper machine, being the same type as the one 
described to make rag and writing paper, only it is much heavier, 
costlier and runs faster. 



CHAPTER XXVI 
EXPLOSIVES 

An explosive is a substance, or mixture of substances, which 
by s proper means may be caused to decompose with great violence 
in such a way as to produce useful results, such as the shattering 
of rock or the propulsion of projectiles. A great many substances 
which may be classed as explosives are now known to chemistry, 
but for practical purposes only those explosives which can be 
cheaply manufactured on a large scale are of commercial impor- 
tance. 

BLACK POWDER. Black powder, or ordinary gunpowder, 
was the only explosive in general use up to the latter half of the 
nineteenth century. It is said to have been discovered in the 
thirteenth century, but its origin as well as the identity of its 
inventor is involved in an obscurity which probably can never 
be cleared. The first powder mill is said to have been erected at 
Augsburg in 1340, and from that time to this black powder has 
retained, with very slight variations, the composition given to it 
by the first powder makers. Although inferior in strength to 
many explosives recently discovered it is still being manufactured 
on an enormous scale. 

For a long time after its discovery black powder was used 
exclusively for military purposes. Its peaceful application to the 
mining industry began about two hundred years ago. 

The Raw Materials of Black Powder. The potassium 

nitrate (saltpeter) used in manufacturing black powder is either 
" natural " saltpeter or the so-called " conversion " saltpeter. 
" Natural " saltpeter is obtained by subjecting nitrogenous 
organic matter to decay in the presence of wood ashes. It has 
been manufactured in this manner from early times on a large 
scale in India. " Conversion " saltpeter is obtained by treating 
a solution of potassium chloride (Stassfurt salts) with the solu- 
tion of a soluble nitrate, such as sodium nitrate from the Chile 
nitrate fields. 

Natural saltpeter is preferred for powder making, since the 

470 



EXPLOSIVES 471 

conversion saltpeter frequently contains traces of potassium or 
sodium perchlorates, the presence of which makes the powder 
less uniform and less reliable. The better grades of sporting 
and military black powders are made from the natural saltpeter. 

Charcoal which has been made by charring peeled, well- 
seasoned willow wood is preferred for powder making, although 
many other kinds of wood, and even hemp, flax and straw are 
used. For certain kinds of powder it is required that as much 
as possible of the volatile matter be driven off. For other kinds 
the wood is only partly carbonized, when the charcoal, instead of 
being black, has a red or brown appearance. These brown coals 
are used for making sporting powders and were formerly used 
exclusively in military powders for large caliber guns. 

The sulphur used in black powder manufacture is ordinary 
sulphur as free as possible from impurities. 

Process of Manufacture. The technical process of mix- 
ing these ingredients involves a number of separate operations as 
follows: 

1. Pulverizing the raw materials; 5. Drying; 

2. Mixing the raw materials; 6. Dusting and sorting; 

3. Compressing; 7. Polishing; 

4. Graining; 8. Blending. 

The raw materials are first pulverized in revolving drums 
containing bronze balls. For this operation they are taken in 
pairs; that is, saltpeter and sulphur; saltpeter and charcoal; 
charcoal and sulphur. The different pairs are then mixed in 
proper proportion and further ground in the ball-mill. In this 
condition the powder is known as " meal " and may be used 
without further treatment for making fireworks or fuses. It is 
not, however, in a form suitable for blasting or for use in firearms. 

The grinding in the ball-mill serves merely as a preliminary 
mixing. To secure a more thorough incorporation of the raw 
materials, the meal is next ground in a mill provided with heavy 
edge runners. This is a type of mill extensively used in many 
industries (Fig. 6), and consists of two heavy, broad-edged wheels, 
connected by a short axle which is caused to revolve horizontally 
by an upright shaft. The two wheels or runners travel around a 
circular basin which contains the material to be ground, and which 
is subjected to a conbined crushing and grinding action. This 
operation lasts about four hours. Before grinding under the edge- 
runners about 10 per cent of water is added to the powder to 



472 ELEMENTS OF INDUSTRIAL CHEMISTRY 

reduce the danger of explosion by friction. In spite of all pre- 
cautions the mass frequently explodes, and for this reason no 
person is allowed in the grinding room while the runners are in 
motion, the mills being started and stopped from a distance. 

After the grinding is complete the mass is pressed into sheets, 
and the sheets subjected to further pressure and consolidation 
in a hydraulic press. The pressure employed in these hydraulic 
presses varies from 100 to 110 atmospheres, the powder remaining 
in the press for from one-half to two hours. Sporting powders 
are pressed so as to obtain a specific gravity of 1.7 or 1.8, while 
the specific gravity of blasting powders is only about 1.5. 

The cakes are next broken up and the fragments passed through 
sieves of different mesh, which sort the material into grains of 
uniform sizes, the grains ranging from 0.3 millimeter to 1.8 milli- 
meters in longest dimension. The next step is to remove the 
greater part of the added water by means of dry air at a moderate 
temperature. When the moisture has been reduced so that the 
powder contains from 1.5 to 3 per cent, depending on the grade, 
it is again sifted so as to remove dust, which is returned to the 
grinding mill. The powder is then polished by rotating in wooden 
drums. This serves to rub off sharp corners. After a further 
sifting to remove dust, the powder is polished by shaking in the 
drum with a small quantity of graphite. Different grades of 
powder may be blended as required, after which the finished 
product is packed for the market in air-tight packages. 

NITROCELLULOSE. Nitrocellulose, or more properly speak- 
ing, cellulose nitrate, is now the chief material used in the manu- 
facture of military and sporting powders throughout the world. 
In conjunction with camphor and other substances it is also largely 
used in making celluloid. 

Nitrocellulose is not a nitro-compound, as chemists now 
understand that term, but is a true nitrate in which the hydroxyl 
groups of the cellulose molecules have been replaced by the nitrate 
radicle (NO3). The inaccurate designation, nitrocellulose, which 
was given to the substance by its early investigators, has, however, 
been so long in use that it is not likely to be supplanted by the 
more correct term. Nitrocellulose is manufactured by subjecting 
cellulose to the action of strong nitric acid under certain definite 
conditions. 

Raw Materials of Nitrocellulose Manufacture. 

The raw materials used in making nitrocellulose are cellulose (in 
the form of wood pulp, tissue paper, cotton wool, or cotton wastes 



EXPLOSIVES 473 

from spinning mills) and sulphuric and nitric acids. For making 
nitrocellulose to be used in the cheaper grades of celluloid and in 
certain cheap commercial explosives wood pulp or paper may be 
used. For making smokeless powders for military use, only the 
best and purest forms of cellulose can be employed, such as 
cleaned and bleached cotton wool and spinning mill wastes. 
The so-called delint cotton is mostly employed. 

Preliminary Treatment of the Cellulose. The cotton 
wool or wastes must first be deprived of all impurities, such as 
oil, fat, or dirt. This is done by boiling with dilute alkali. This 
treatment is next followed by light bleaching by means of calcium 
hypochlorite, for the purpose of removing lignin substances that 
form unstable nitrates which would impair the stability of the 
product. Too vigorous a bleaching is to be avoided, as other- 
wise hydrocelliiloses or oxy-celluloses would result and give rise 
to unstable nitrates. 

Before the bleached cotton is subjected to the nitration it is 
dried so as to reduce its moisture content below 1 per cent. For 
this result exposure to a temperature of 105° C. for several hours 
is usually necessary. 

The^ Process of Nitration. Nitrocellulose is not a 
definite compound of invariable composition like calcium nitrate. 
The cellulose molecule can be made to take up about 14 per 
cent of nitrogen, but below this maximum products of many 
degrees of nitration can be obtained. Products of similar nitro- 
gen content prepared under closely similar conditions may differ 
widely in properties. For this reason practical operations have 
to be carried on with great attention to detail. 

The process of manufacture in outline consists in dipping the 
cotton into a mixture of strong nitric and sulphuric acids, allow- 
ing to stand for a short time, and then removing the acid and 
purifying the nitrocellulose. The degree of nitration and the prop- 
erties of the product are dependent on the temperature of nitra- 
tion, duration of the action of the acids, ratio of the mass of 
cotton to the mass of acids, and relative proportions of sulphuric 
acid, nitric acid, and water in the acid mixture. A variation in 
any one of these factors affects the degree of nitration. 

Nitrocellulose for use in military smokeless powders is made 
by nitrating cotton at 30° C. with a mixed acid containing 63 
parts sulphuric acid, 22 parts nitric acid and 53 parts of water. 
A nitrocellulose thus made will have a nitrogen content of from 
12.50 to 12.70 per cent and will be completely soluble in a mixture 



474 ELEMENTS OF INDUSTRIAL CHEMISTRY 

of 2 parts of ether and 1 part of alcohol. Nitrocellulose of over 
12.75 per cent is generally insoluble in the ether-alcohol mixture. 
Nitrocellulose containing 13.10 to 13.40 per cent of nitrogen is 
chiefly used for small arm powders and submarine mines. Nitro- 
cellulose for use in celluloid manufacture and for making artificial 
silk contains from 8 to 11 per cent of nitrogen. 

There are several forms of apparatus used in the operation of 
nitrating. The most general practice is to conduct the operation 
in a lead-lined iron pot or centrifuge. The mixed acid of the 
desired strength, which has been warmed to the required tempera- 
ture, is run in through a pipe leading from the acid reservoir, 
and the requisite amount of cotton is submerged in the acid. 
The bowl of the centrifuge is then covered and allowed to stand 
undisturbed for the requisite length of time. The fumes given 
off during the reaction are led away through a wide pipe. At 
the end of the nitration, the centrifuge is set in motion and the 
excess of acid removed from the nitrated product by centrifugal 
force. The nitrocellulose is taken out of the bowl with pitch- 
forks, thrown into large tanks filled with water, whereupon the 
centrifuge is ready for a new charge. 

The reaction whereby nitrocellulose is formed from cellulose 
and nitric acid is as follows : 

C24H4o02o+nHN03 = C24H 4 o-n0 2 o(N0 2 ) n . 

In this equation n represents any number between 1 and 11. 

The sulphuric acid, which constitutes more than three-fifths 
of the acid mixture, takes no direct part in this reaction, its func- 
tion being to absorb the water resulting from the chemical process, 
thereby keeping the nitric acid up to its full strength. This is 
the usual explanation of the reason for using sulphuric acid, 
although it may not be the true one. 

Purifying the Nitrocellulose. The nitrocellulose re- 
quires thorough purification in order to prevent it from under- 
going spontaneous decomposition at some later period of use or 
storage. To effect this purification it is repeatedly washed and 
boiled with clean water; but a simple boiling, even if prolonged, 
is not sufficient. The cotton fiber is hollow, and in this hollow 
space traces of acid and by-products may remain to cause trouble 
later on. To insure the complete removal of these impurities 
the crude nitrocellulose, after a preliminary boiling, is finely 
pulped in a " beater," very much like the " beaters " used in 



EXPLOSIVES 475 

paper mills, after which it is repeatedly boiled and washed in 
fresh water. 

The attainment of a satisfactory degree of purification is 
recognized by heating a sample of the product, contained in a 
test tube in which is suspended a strip of filter paper which has 
been dipped in a solution of potassium iodide and starch, to 65° 
C. If no iodine is liberated within sixty minutes, the nitrocellu- 
lose is regarded as stable; otherwise the washing and boiling 
must be continued. The whole process of boiling, washing, and 
pulping usually requires several days. 

When finally purity has been obtained the nitrocellulose is 
usually worked immediately into the finished products. Where 
such working up cannot be at once proceeded with it is kept 
under w-ater, or in a very moist state, to obviate the danger of 
explosion. If it has to be dried, this operation must be conducted 
with care for the same reason. Nitrocellulose is seldom stored 
or transported unless it contains at least 15 per cent of w T ater. 
In outward appearance nitrocellulose does not differ from the 
cotton from which it is made, except that it has a somewhat 
harsher feel. 

SMOKELESS POWDERS. Powders made from nitrocellulose 
and other pure organic nitro-compounds are called smokeless 
powders on account of their comparative freedom from ash. 
Black pow r der, as has been said before, wmen burned leaves be- 
hind over one-half its weight of solid products, which naturally 
give rise to dense clouds of smoke. As the mineral matter of 
nitrocellulose rarefy exceeds 0.5 per cent the residue left on com- 
bustion of powders made from it gives rise to very little smoke. 

Owing to its extreme rapidity of combustion, pure nitrocellu- 
lose cannot be used in firearms, but must be made into a form 
wherein the rate of combustion is greatly reduced, otherwise the 
gun or cannon might be shattered. This transformation is effected 
by working the nitrocellulose into a stiff dough with a small amount 
of ether-alcohol mixture. The plastic mass thus formed is then 
run through a press similar to a macaroni press, which forms 
it into long rods having one or more axial perforations. In 
most cases there are seven of these perforations. These rods are 
then cut into suitable lengths, each length constituting a " grain " 
of the powder. The heavier the gun in which the powder is to 
be used, the larger are these " grains." For example, a " grain " 
of powder for a 12-in. gun is about 3 ins. long with a diameter of 
about f in. Not all military powders have the same form, 



476 ELEMENTS OF INDUSTEIAL CHEMISTRY 

however, as the ordnance experts of the different countries have 
different preferences in the matter. 

The final step in making smokeless powder is to reduce the 
content of volatile matter, water, alcohol and ether by drying to 
within certain very definite limits. 

Instead of working the nitrocellulose into a colloidal mass 
with ether-alcohol, acetone may be used either alone or in con- 
junction with nitroglycerin, or other nitro-compounds. Nitro- 
cellulose powders with a nitroglycerin base are more uniform 
and reliable than straight nitrocellulose powders, but are more 
corrosive to the interior surface of the gun. The military powders 
for large caliber guns used by the United States, France and 
most other countries, are straight nitrocellulose powders. The 
English military smokeless powder is a nitroglycerin-nitrocellu- 
lose mixture, and is known as " cordite." 

STABILIZERS. It is customary to add to the military smoke- 
less powder a small amount of " stabilizer/' such as diphenyl- 
amine, which absorbs any nitrogen oxides which may be split 
off by spontaneous decomposition during the storage of the powder. 
In the absence of a stabilizer these free oxides are liable in time 
to cause spontaneous explosions, which have been attended in 
recent years with disastrous results to ships of war. 

NlTRO-STARCH. Nitro-starch, or rather starch nitrate, has 
lately been successfully manufactured for use as a blasting explo- 
sive in smokeless powders, and in general for all purposes to which 
nitrated cotton is put. Cassava starch is the most suitable variety 
for this purpose. The process of manufacture differs somewhat 
from the manufacture of nitrocellulose, the points of difference 
being in the use of stronger acids, and appropriate means for 
mixing the starch with the acid and separating the product 
therefrom. The advantage of starch over cotton is its compara- 
tive cheapness. The nitro-starch is more difficult to stabilize 
than the nitro-cotton. The methods used in making it are as 
yet trade secrets. However, nitro-starch has attained only 
relatively small importance commercially. 

Nitroglycerin and Dynamite. Explosives composed 

wholly or in part of nitroglycerin and closely related substances 
are at the present time the most important of industrial explosives. 
Nitroglycerin is formed from nitric acid and glycerin in 
accordance with the following reaction: 

C 3 H5(OH)3+3HN03 = C3H5(N03)3+3H 2 0. 



EXPLOSIVES 477 

Nitroglycerin, like the analogous product of the interaction of 
nitric acid and cellulose, is a true nitrate and not a nitro-compound. 
The term " nitroglycerin " is therefore a misnomer, which, how- 
ever, is apparently too well intrenched in common usage to make 
way for the more appropriate name. 

The process of manufacture consists simply in adding the 
glycerine to the mixed acids as in the case of nitrocellulose, sep- 
arating the glycerine nitrate from the mixed acids and purifying 
it. The methods used in practice for carrying out this simple 
reaction, however, are very diverse, and for full details thereon 
reference must be had to larger treatises such as 0. Guttmann's 
" Manufacture of Explosives/' or Kedesdey's " Sprengstoffe." 

DYNAMITE. Nitroglycerin is a heavy oily liquid and in this 
form has but a limited applicability. For convenience in use it 
must be put into a form wherein it may be easily handled. This 
is done by causing it to be absorbed by various porous bodies, 
such as infusorial earth, or kieselguhr, which can be made to 
absorb three times its weight of nitroglycerin. Such a mixture 
of nitroglycerin and kieselguhr forms an earthy, friable mass, 
which can be loaded into paraffined paper cartridges and is sold 
under the name of 75 per cent dynamite, or No. 1 giant powder. 
This is the original dynamite as manufactured by its inventor, 
Nobel. 

Dynamites are generally classified according to the amount of 
nitroglycerin content. Thus, a 50 per cent dynamite means a 
dynamite containing 50 per cent of nitroglycerin. 

GELATIN DYNAMITE. Nitroglycerin^ has the property of 
dissolving nitrocellulose to a limited extent. A mixture of approx- 
imately 9 parts of nitroglycerin and 1 part of nitrocellulose forms 
a clear, jelly-like mass containing no inert matter, which con- 
stitutes a powerful explosive. The name gelatin dynamite is 
applied to this product on account of its jelly-like consistency, 
and not because it contains gelatin. 

Aromatic Nitro-compounds used as Explosives. Chief 

among these is picric acid, C6H 2 (OH)(N02)3, which is the trinitro 
derivative of phenol (carbolic acid). It is made by heating equal 
parts of phenol and sulphuric acid at 100-120° C, until the two 
substances have united to form phenol-sulphuric acid. This 
product is then dissolved in double its weight of water, the mixture 
being then poured into concentrated nitric acid. The resulting 
picric acid is separated in centrifuges. Picric acid, either as 
such or in the form of its ammonium salt, is used as a bursting 



478 ELEMENTS OF INDUSTRIAL CHEMISTRY 

charge in armor-piercing shells for guns of high caliber. The 
famous " shimose " of the Japanese is simply picric acid in com- 
pact form, obtained by melting and pouring into the shell. The 
reason for employing picric acid in shells is that besides having 
certain other desirable properties, it is the most powerful explosive 
known. 

Picric acid, although a very powerful explosive, cannot be 
set off except through shock produced by special means. Its 
salts, other than the ammonium salt, are much more easily 
exploded than the acid itself. 

Trinitrotoluol has been used by the United States and other 
governments as a high explosive for military purposes. Trin- 
itrobenzol, trinitroanisol and other substances of similar consti- 
tution have also been used for the same purpose. Picric acid 
and trinitrotoluol are used to a limited extent as industrial 
explosives, but are considered too expensive for general use. 

SAFETY POWDERS. The necessity of adapting the composi- 
tion of an explosive to the conditions under which it is used is 
exemplified in coal mining, where there is the ever present danger 
of igniting the dreaded " fire damp." An explosive mixture of 
air and methane will ignite only when locally heated above a 
certain critical temperature for a sufficient time, or brought in 
contact with an open flame of sufficient duration. To be used 
with safety in a gassy coal mine, an explosive must not give rise 
to either of these conditions. Safety explosives of this character 
are now manufactured in fairly large number. A list of per- 
mitted explosives, which may be used with fair safety in coal mines, 
is published by the U. S. Bureau of Mines. 

FLAMELESS EXPLOSIVES. For certain purposes other than 
blasting in coal mines it is desirable to suppress as much as possi- 
ble the amount of heat and flame produced when an explosive is 
set off. In military operations with artillery at night a gun 
producing much flame would disclose the position of the battery 
to the enemy and, moreover, excessive heat erodes the interior 
of the gun, decreasing its life. To obviate these effects, which are 
chiefly noticeable with nitroglycerin mixtures, the powder may be 
mixed with substances like oxalic acid (Maxim's patent), vaseline, 
alkaline resinates, etc., which decompose under the effects of 
heat, producing much gas, which tends to dilute and thus lower 
the temperature of the gases evolved from the explosive proper. 
The amount of flame and the erosive action may thus be materially 
reduced without great sacrifice of ballistic efficiency. 



EXPLOSIVES 479 

FULMINANTS, PRIMERS, OR DETONATORS. Explosives may 
be divided into two general classes according to the means required 
to set them off or bring about their decomposition with explo- 
sive effect. The first class includes those which are set off by^sim- 
ple ignition. To this class belong black powder and nitrocellu- 
lose. When a lighted match is applied to black powder, the 
part first heated begins to burn with great rapidity, the com- 
bustion being supported by the materials contained in the explo- 
sive itself, i.e., there is induced a chemical action between the 
potassium nitrate on the one hand and the carbon and sulphur 
on the other. The resulting process of combustion is rapidly 
propagated throughout the mass and there is suddenly produced 
a large volume of hot gas with an enormous expansive force. 
Comparatively speaking, however, the wave of combustion in 
black powder travels at a low speed. The force of the explo- 
sion, therefore, develops slowly and its rate of development is 
easily capable of measurement. 

The second class of explosives here considered are those whose 
explosive effects are not developed by mere ignition. Dynamite 
and picric acid, for example, when set on fire under certain con- 
ditions merely burn, without necessarily producing an explosive 
effect. If, however, picric acid or nitroglycerin (and under 
certain conditions, nitrocellulose also) be confined in a small 
space and struck a sharp blow, there is set up an explosive wave 
of decomposition, distinct from the wave of combustion, the 
difference between the two being that the former is propagated 
with practically immeasurable velocity. In order to bring about 
the maximum effect of such an explosive, it is therefore necessary 
to induce an explosive wave in its mass, and this in practice is 
accomplished by the use of a " priming charge," consisting of a 
small amount of some explosive which decomposes with extraor- 
dinary velocity. Such primers are the salts of fulminic acid, 
the most important being mercury fulminate. So great is the rate 
of decomposition of this substance when heated or struck that the 
expansion of the evolved gas has the effect of a blow delivered 
by a mass moving at a velocity infinitely great. The shock so 
produced against the adjacent mass of picric acid or similar body 
is translated into a wave of decomposition, which instantaneously 
transforms it into gaseous products. 

Mercury fulminate can be made to set off black powder and all 
other explosive mixtures. It is used in the form of caps or deto- 
nators in practically every instance where an explosion is to be 



480 ELEMENTS OF INDUSTRIAL CHEMISTRY 

brought about, whether for industrial, sporting, or military pur- 
poses. All shells ased in modern warfare carry special detonators 
of mercury fulminate for setting off their bursting charges. 

Mercury fulminate is made by dissolving mercury in nitric 
acid in the presence of alcohol. Its manufacture and handling 
are very dangerous. 

A good substitute for mercury fulminate in primers is a mixture 
of potassium chlorate with powdered glass, and antimony tri- 
sulphide or various metallic thiosulphates. Such primary mix- 
tures are safer to handle than the fulminate, and for this reason 
are, growing in favor. 



CHAPTER XXVII 
LEATHER 

When the pelts of animals are allowed to remain moist they 
soon putrefy, while if dried they become hard and horny. To 
obviate these conditions, certain processes known as tanning are 
employed. The object of this treatment is to convert the putres- 
cible animal matter into a material which is permanent, and 
at the same time possessing sufficient softness or flexibility for 
the purposes for which it is intended. As these range from heavy 
sole leather to light kid, there are wide divergences in the 
processes employed, materials used, and the methods of 
their application. 

STRUCTURE OF THE SKIN. The skins of the various animals 
at first glance seem to have very little in common; on closer 
examination, however, it will be seen that they all have a similar 
structure, though on account of the difference in texture and thick- 
ness their practical application differs very greatly. The skins 
of lizards, alligators, fishes and serpents differ from the higher 
animals in that the epidermis becomes harder and forms scales. 

The skin is not merely a covering for the animal, but is at the 
same time the seat of the organs of sense and produces cercain 
important secretions. It consists of two principal layers, the 
epidermis (epithelium, cuticle) and the corium (derma, cutis, or 
true skin) . The epidermis is very thin as compared with the true 
skin which it covers, and is entirely removed preparatory to 
tanning; it nevertheless possesses important functions. Its 
inner mucous layer, which rests upon the true skin, is soft, and 
composed of living nucleated cells, which multiply by division 
and form cell-walls of keratin. These are elongated in the deeper 
layers, and gradually become flattened as they approach the sur- 
face, where they dry up, and form the horny layer. This last is 
being constantly worn away, thrown off as dead scales of skin, 
and as constantly renewed from below, by the multiplication of 
the cells. 

It is from the epithelial layer that the hair, as well as the 

481 



482 ELEMENTS OF INDUSTRIAL CHEMISTRY 

sweat and fat glands, are developed. Each hair is surrounded 
by a sheath which is continuous with the epidermis, and in which 
the young hair usually grows as the old one falls out. Near the 
openings of the hair-sheath upon the surface of the skin the ducts 
of the sebaceous or fat glands pass into the sheath and secrete 
a sort of oil to lubricate the hair. The base of the hair is a bulb, 
enclosing the hair "papilla, which is a projecting knob of the 
true skin and which by means of the blood-vessels contained in it 
supplies nourishment to the hair. The hair bulb is composed of 
round soft cells, which multiply rapidly, and pressing upward 
through the hair sheath, become hardened, thus increasing the 
length of the hair. 

The structure of the corium or true skin is quite different 
from that of the epidermis. It. is composed principally of inter- 
lacing bundles of fibers, known as connective tissue, which are 
cemented together by a substance more soluble than the fibers 
themselves. These fiber-bundles are more loosely interwoven 
in the middle portion of the skin, but become compact again 
near the flesh. The outermost layer, just beneath the epidermis, 
is also very close and compact. The skin is united to the animal 
by a network of connective tissue (panniculus adiposus), which 
is frequently full of fat cells, and is then called adipose tissue. 
This portion, together with some actual flesh, is removed in the 
process of fleshing. 

Ordinarily the corium or true skin is the only portion which 
is used in the production of leather. In order to obtain it in a 
suitable condition for the various tanning processes, the hair 
or wool, together with the epithelium, must be completely removed 
without damaging the skin itself; and especial care must be taken 
that the grain, or portion next the epidermis, does not suffer 
injury during the treatment. 

CLASSIFICATION OF PELTS. The pelts of animals come to 
the tanner in three conditions as green (fresh from the animal), 
salted (where salt has been rubbed on the flesh side), or dried 
(usually stretched on boards in the sun). The pelts so received 
are divided according to their size into three general classes, 
namely: hides, comprising the skins from large and fully grown 
animals, such as the cow, horse, camel, walrus. These form 
thick heavy leather, used for shoe soles, machinery belting and 
other purposes where stiffness and strength, combined with 
wearing qualities, are necessary. They are also cut into splits 
for use as shoe uppers, bag and case leather, automobile and 



LEATHER 483 

carriage tops, furniture and upholstering. Kips are the skins of 
undersized animals of the above species. Skins are obtained 
from small animals, such as calces, sheep and goats. Kips 
and skins yield a lighter leather than hides. This is suitable for 
a great variety of purposes, such as uppers for shoes, pocket 
books, book bindings, gloves and fancy leather. Pelts vary in 
thickness and texture in different parts, being thicker on the neck 
and butt than on the flank and belly. The same species vary 
greatly, according to climatic conditions under which they are 
raised, and to their breeding and feed. They often show injury, 
such as cuts, brand marks, and sores caused by the bot-fly or 
warble. 

SOAKING. Whether the skins are green, salted, or dried 
they must first be soaked in water in order to remove the dirt 
and blood in the case of green skins, salt in the salted skins, and 
for the purpose of softening in the case of dried skins. It is 
very essential that the skins should be free from all foreign 
matter before entering the limes or other unhairing solutions, as 
the presence of salt greatly retards the plumping; while the 
presence of albuminous matter is apt to set up an undesirable 
fermentation in the after treatments. When perfectly soft and 
well washed the skins are removed from the soaks, thrown over a 
rounded beam, tails and ear-laps trimmed, and any adhering 
portions of flesh removed. 

The time of soaking varies from one or two days to several 
weeks, depending upon the thickness of the hide and the age and 
temperature of the soak. Putrid soaks soften much quicker 
than fresh ones; but great care is necessary in using them lest 
the decomposition attack the hide fiber itself. For heavy hides 
which soften very slowly it is found to be of advantage to run in 
a drum for a short time with water at a temperature of about 
40° F., the tumbling movement thus materially aiding in the soft- 
ening process. 

The addition of small amounts of alkali or acid to the soak 
water has a material advantage in shortening the time of soaking 
as well as preventing the excessive loss of hide substance. For 
this purpose 0.1 per cent of caustic soda on the weight of the water 
is very satisfactory. Sodium sulphide, borax, and sodium car- 
bonate may also be employed, in which case about 0.3 per cent 
should be taken. During the past few years formic acid has 
come into use for this purpose, about 0.1 per cent of the weight 
of the water being introduced. 



484 ELEMENTS OF INDUSTRIAL CHEMISTRY 

FLESHING. After being soaked, the skins are fleshed. 
This operation is for the purpose of removing any fat or flesh 
which has been left on the pelt by the butcher, and consists in 
working the hide over a beam in a somewhat similar manner 
to that described for unhairing, except that the knife employed 
is heavier and is sharp on both sides. In nearly all modern 
tanneries, however, the beam has been displaced by machines 
for the purpose. 

The type of machine employed for fleshing skins differs some- 
what from that used for hides, although the operation is similar 
in-each. The essential feature of the machine consists in a cylinder 
provided with spiral blades, which are arranged right handed on 
one side, and left handed on the other. By means of this kind of 
blade the flesh is easily removed, and the hide stretched in all 
directions. 

DEPILATION. By the term depilation is meant the removing 
of the hair and epidermis. This is necessary in all kinds of leather, 
except that to be used for furs, the soft mucous matter of the 
epidermis becoming affected, thus loosening the hair without 
materially injuring the true skin. 

Sweating. The oldest method of depilation seems to have 
been by means of incipient putrefaction, or as it is called " sweat- 
ing." The hides were allowed to remain in piles in a warm, 
damp room until the mucous matter connecting the epidermis 
with the dermis had decomposed, which thus loosened the hair 
without injuring the true skin. This method, however, often 
resulted in damaged stock and so the process was improved 
upon by allowing the hides to hang in a closed, damp room 
or cellar called a " sweat pit." 

Liming. Lime is the agent generally employed for unhairing, 
although it also has its disadvantages. In preparing the lime 
solution a quantity of fresh lime (calcium oxide) is slaked by 
placing in a shallow tank, similar to that used by builders, and 
adding sufficient water to thoroughly moisten it. At the end 
of one or two hours it becomes heated and falls to a powder. 
Sufficient water is added to form a thick paste, in which con- 
dition it may be kept for several weeks or even months without 
much change. When required for use a suitable amount is dug 
out, stirred with water to remove rocks, and then run into the pits. 

The usual method of liming is to lay the hides one at a time in 
the lime solution, taking care that each hide is well immersed 
before entering the next one. The hides are taken out (hauled) 



LEATHER 485 

each day and the liquor well plunged up, in order to distribute the 
undissolved lime throughout the pit. They are then thrown back 
(set), care being taken to see that they are fully spread out. In 
some tanyards the hides are joined by hooks (toggled) and reeled 
from one pit to another, or to the same pit. Sometimes hides 
are suspended in the liquor, and by means of a paddle, or by 
blowing in air, the limes are kept in motion. The most common 
method, however, where it is desired to agitate the liquor, is to 
employ the ordinary paddle box and run it at intervals during 
the day. 

The action of lime on the hide is to swell up and soften the 
epidermis cells, dissolve the mucous layer and loosen the hair, 
so that on scraping with a blunt knife both the epidermis and hair 
are easily removed. The action on the true skin is very vigorous, 
causing the hide to become plump and swollen, and at the same 
time dissolving the cementing material of the fibers, thus causing 
them to become split up into finer fibrils. This swelling is prob- 
ably caused by the formation of a lime soap, due to the union 
of the lime with the fatty matter of the hide. Not only does the 
liming process remove the hair and epidermis, but it also is of 
value in the fleshing process, as it gives to the hide a greater 
firmness, which is very desirable when working with the knife 
or on the machine. The time of liming varies with the season of 
the year, with the kind of skins treated, and may be from three 
to fifteen days. The age of the lime has a great influence on the 
time of treatment as well as on the character of the finished 
product. Old limes unhair much quicker than fresh ones. It is 
often customary to place the hides in an old lime for several 
days, or until the hair and epidermis have started to loosen, then 
change them to a fresh lime, which produces the desired plump- 
ing of the fibers. Great care, however, must be taken that the 
limes do not become too old, as this condition will be very apt, 
especially in hot weather, to produce a transparent swelling of 
the tissue with destruction to the fiber. 

Arsenic Sulphide. When the red sulphide of arsenic, AS2S2, is 
dissolved in hot water and added to lime it increases its depilating 
effect. It is emploj-ed especially in fine leathers, to which it 
gives the necessary stretch, softness, and clearness of grain, 
without the loss of hide-substance and the loosening effect cased 
by ordinary liming. The amount used varies somewhat, but 
may be said to run from 0.1 to 0.4 per cent of realgar and 4 to 
6 per cent of lime, reckoned on the weight of the green skins. 



486 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Sodium Sulphide. This substance when employed in strong 
solution, 5 per cent or over, has the effect of rapidly reducing the 
hair and epidermis to a sort of pulp, which may be easily swept 
off with a broom, or even washed off in the drum. The operation 
is usually conducted in a paddle, and takes about two hours for 
the complete removal of the hair and epidermis. The action on 
the hide-substance, and especially upon the cementing material, 
is very slight, although the grain is swollen and temporarily 
rendered somewhat tender. As this strong solution destroys 
the hair it is only used on such stock as goat skins, where the hair 
is of minor importance. On the other hand, when used in weak 
solutions, 0.25 per cent or less, in conjunction with lime, the hair 
is but little injured, the hair-roots and dirt being rapidly loosened 
with a result somewhat similar to that produced by arsenic 
sulphide. 

Arazym. It has recently been discovered by Dr. Otto Rohm 
that hides and skins can be unhaired and bated in one operation 
by means of tryptase in an alkaline solution; which, if it proves 
successful from a practical standpoint, will eliminate the old-time 
beam house methods. In conducting this process the soaked 
and fleshed stock is introduced into a 0.1 per cent solution of 
caustic soda for twenty-four hours to allow them to plump and 
thus open up the fiber bundles. The caustic soda is then drawn 
off, the skins washed in running water for a short time and 
enough sodium bicarbonate to make a 0.1 per cent solution 
introduced. The temperature of the water is raised to 90° F. 
and then sufficient arazym to give a 0.1 per cent solution added. 
The stock is run in this solution for twenty-four to forty-eight 
hours or until unhaired. 

UNHAIRING. When the process of depilation is complete 
the skins or hides are removed from the pits and allowed to drain 
for half an hour or more. They are then placed on the beam and 
the hair removed. In recent years various machines have been 
devised to accomplish the removal of the hair, and these have 
been brought to such perfection that the old method of hand work 
has been almost entirely eliminated in the modern tannery. 
The unhairing machine is provided with a spiral, blunt knife 
which revolves on a rubber roller. 

BATING. It is very essential that the lime, or other depilat- 
ing agent, should be completely removed when it has done its 
work, since its action is very harmful when brought in contact 
with tanning materials. The presence of lime also has a tendency 



LEATHER 487 

to weaken the fiber and to produce a harsh-feeling product as 
well as to cause a loss in the materials employed in the currying 
and finishing processes. For most leather it is not only necessary 
that the lime be completely removed, but that the skin should 
be brought from its swollen to a soft and open condition. To 
accomplish this with the heavier classes of dressing leather, 
such as split hides, kips, colt and calfskins, the stock is run in a 
weak fermenting infusion of pigeon- or hen-manure. The time 
of immersion depends upon the strength of the liquor and upon the 
nature of the pelts under treatment. 

PUERING. This is a process very similar to bating, applied to 
the finer and lighter skins, such as glove- and glace-kids and mo- 
roccos, in which dog-manure is substituted for that of birds. As the 
mixture is used warm and the skins are thin, the process is com- 
plete in a few hours. Neither bating nor puering are very effec- 
tive in removing lime, but seem to act upon the hide substance 
by means of bacterial products, causing the pelt to fall, that is, 
to become soft and flaccid. Great care must be exercised in this 
treatment, in order to prevent possible decomposition of the hide, 
or what is known as " running of the grain," that is, if the action 
becomes local and the grain is eaten away in spots. During 
electrical storms the action becomes very much intensified, and 
may result in a complete decomposition of the pack, unless the 
skins are drawn out or the liquor greatly diluted. 

When the skins are removed from the dung infusion they are 
slightly alkaline in reaction from excess of lime and ammonia, 
which must be removed before they are ready for the actual 
tanning process. The neutralization is accomplished in various 
ways, and is known as drenching and pickling. 

PATENT BATES. During the past few years several patented 
bates have been introduced, which have replaced the older methods 
to a very large extent. These bates are of a chemical nature, 
a fermentative nature, or a combination of the two. Of all of 
these preparations the ones which are being used at present are 
the following: 

Oropon. This material is composed of ammonium chloride, 
wood fiber and dry pancreas. It is put on the market as a dry 
powder and has the advantage that no previous preparation is 
accessary. The quantity required is from J to 1 per cent of the 
weight of the stock at a temperature of from 90° to 100° F. The 
first action is the neutralization of the lime by the ammonium 
chloride, which causes the stock to fall at once; the enzymes then 



488 ELEMENTS OF INDUSTRIAL CHEMISTRY 

exert a solvent action upon the cementing material of the hide, 
causing it to become open. 

Dermiforma. This is a preparation composed of whey, lactic 
acid and other organic acids. It comes on the market as a liquid 
and is used at the same temperature as other bates. 

Puerine. This compound must be fermented before use. 
Once started, however, it can be run for several months, it only 
being necessary to add fresh material for that which has become 
exhausted. 

CHEMICAL BATES. For certain classes of leather the use of 
ammonium butyrate, lactic acid or formic acid have been found 
to give very satisfactory results. Each of these is a very active 
deliming agent. Ammonium chloride has a solvent action upon 
the lime and is used in many of the patent bates. Boric acid is 
rather widely employed, as it not only has the power of removing 
the depilating agent, but hastens the tannage, gives a good color 
and a smooth grain. In all of the processes where chemicals 
only are employed the results obtained differ from those where 
bacterial bates are used. 

DRENCHING. Drenching is sometimes used as a substitute 
for bating, but usually follows the bating process. It not only 
serves to remove the lime completely, but tends to slightly plump 
the skins. The drench liquor is prepared by allowing an infusion 
of bran in warm water to ferment under the action of special 
bacteria which develop lactic and acetic acids. When a bath is 
once prepared it can be used continuously by drawing off part of 
the liquor, and adding fresh portions of bran and water. In 
neutralizing by this method the skins are entered, and the liquor 
moved occasionally to get a uniform contact. As fermentation 
becomes well established during the night, the skins will rise to 
the top, on account of the gas produced. The night watchman 
then forces them under again, by means of a heavy pole. On 
rising a second time they are free from lime, and in a soft and 
open condition. This open condition is very essential in soft 
leather, but is not desirable in harness or other kinds of firm and 
heavy leather. 

PICKLING. This method usually consists in drumming the 
skins in a concentrated salt solution to which a small amount of 
sulphuric acid is added. The ratio between salt and acid is 
usually 8 pounds of salt to 1 pound of acid. The solution should 
stand 1.060 sp.gr. (8° Be., 12° Tw., 60° Bk.). In some tanneries 
the pickling is carried out in the paddle, and fresh acid introduced 



LEATHER 489 

after each pack has been removed. If the pickle has the correct 
acid strength 15 cc. of normal sodium hydroxide will neutralize 
100 cc. of the liquor, using phenolphthalein as an indicator. 
The salt should be replenished by adding a sufficient amount to 
keep the specific gravity up to 1.060. 

The Tanning Operation. The term " tanning " origi- 
nally was applied to the treatment of hides and skins with some 
vegetable product containing tannic acid. With the introduction 
of chemical methods for preserving the hide substance the old 
term has still been retained; so that the process of tanning may 
mean either a treatment with mineral salts, oils, or aldehydes, 
as well as those methods in which vegetable substances containing 
tannic acid are employed. 

VEGETABLE TANNAGE. For the actual tanning operation, 
the liquor used depends entirely upon the nature of the skins 
or hides, and upon the kind of leather it is desired to produce. 
There are three general methods, however, which are in common 
use. The first method consists in suspending the stock in a 
solution of the tanning material. The second method is carried 
out in a paddle so that the stock is kept in constant motion dur- 
ing the whole or part of the operation. The third method con- 
sists in tumbling the stock in a drum or pin mill during the whole 
or part of the operation. In the heavy hides the time of treat- 
ment is of course very much longer than is the case with light 
skins. i 

Belt, Sole and Harness Leather. The hides as they 

come from the " beam house " are run in an acid liquor in order 
to neutralize the lime, and to bring them to a plump or swollen 
condition. They are then transferred to the stick pits or sus- 
penders; the name coming from the fact that the hides are sus- 
pended by the butts from sticks placed across the pit. The 
liquor in the first pit is very dilute, and nearly exhausted, having 
a density of about 10° Bk. From day to day the liquor is changed, 
so that a gradual increase in its strength is obtained. After the 
hides have remained in the suspenders from eight to ten days 
they are laid in pits called handlers, where a stronger liquor is 
employed. The weakest liquor from the youngest handler pit 
is run daily to the suspenders, a new and stronger liquor being- 
run into the pit holding the oldest and most tanned pack. As this 
pack is removed the next in age takes its place, while the young- 
est pack enters the pit containing the weakest liquor. In this 
manner each pack receives a change of liquor of graduated 



490 ELEMENTS OF INDUSTRIAL CHEMISTRY 

strength, passing from about 20° Bk. to one of 40° Bk. In the 
handlers the hides are completely struck through or tanned and 
then pass to the layers. In the layers the hides are spread out as 
smoothly as possible and dusted with ground bark, and are 
piled up, alternating a layer of hides with a layer of bark. When 
the pit is full concentrated liquor is run in until the pack is com- 
pletely covered. The hides are allowed to remain undisturbed 
in this condition for several weeks, or until they have taken 
up as much as possible of the tannic acid and other material. 

BLEACHING AND RETANNING. In order to secure a better 
and more uniform color it is customary to " strip " or remove 
a part of the surface tannage by means of borax or weak alkali. 
This is usually carried out in the drum, and the excess of alkali 
neutralized with oxalic, sulphuric, lactic, or formic acids and 
thoroughly washed. The cleared hides are then retanned with 
sumac or other light-colored tanning material. Previous to the 
retanning it is also customary in most shops to remove a small 
skiver from the flesh-side so that the hides will have a uniform 
thickness and similar appearance. 

STUFFING. The object of this operation is to surround the 
fibers with fat and oil, which serves to lubricate them and render 
the leather more pliable, while at the same time it gives to the 
stock more body or weight. The process most commonly em- 
ployed consists in placing the sammied (damp) hides in a drum, 
heated to about 140° F. and running in the melted stuffing material 
through the trunnion. Many kinds of stuffing greases are used. 
One which gives very satisfactory results consists of a mixture 
of tallow and cod oil. After running for about half an hour the 
hides are removed and set out while in a warm condition. This 
setting out is accomplished on a machine similar to that described 
under fleshing. In the setting out the excess of grease is removed 
and the stock given a mild stretching treatment. 

FRAMING. From the setting-out machine the hides are 
placed on frames, where they are given as much of a stretch as 
possible and allowed to dry in a state of tension. 

FINISHING. On removal from the frames the hides are 
given a coat of wax, shellac, gelatin, blood albumen or other 
finishing substance and after rolling on the jack are ready for the 
market. 

In the tanning of heavy leather the above treatment is some- 
times varied by cutting the hides into " bends " and " bellies"; 
or into " butts " and " shoulders." The subsequent treatment 



LEATHER 491 

is somewhat modified for the different portions. The tanning 
materials used for heavy leather vary, consisting either of one 
or several tanning products. The density of the liquor employed 
may also var} r within rather wide limits. 

SOLE LEATHERS. In the manufacture of sole leather, the 
process is very similar to the above. After tanning, however, 
the stock is filled with hot extract, bleached and loaded. It is 
then dried, sammied and rolled. 

Vegetable-tanned Calfskins. In preparing calfskins 
for the tanning process they should be well beamed and bated 
until they are soft and open. The washed skins are then sus- 
pended on sticks and allowed to hang in the tan liquor as described 
under hides. The strength of the liquor, however, may be some- 
what changed, although 8° Bk. is very satisfactory at the start. 
The strength is increased uniformly for six days, when the stock 
should be completely struck through or tanned. The skins are 
then removed from the suspenders, washed and horsed up to 
drain. When in the proper sammied condition they are shaved 
and retanned in sumac, to which a small amount of sulphurous 
acid, oxalic acid, formic acid or formaldehyde is added. The 
retanning may be carried out in a drum, but it is preferable to 
employ the paddle. When the retanning is complete the skins 
are again washed, treated with about 3 per cent of soluble oil, 
set out, and tacked on frames to dry. Having thoroughly dried 
they are removed from the boards, and are ready for the coloring 
and finishing operation. 

Vegetable-tanned Sheepskins. Sheepskins come to the 
tanner in the pickled condition containing sulphuric acid and 
salt. They are usually washed free from the pickle with a strong 
salt solution before they enter the tan liquor. These skins may 
be tanned in pits as described for calfskins, except that it is 
necessary to have a certain amount of salt in the solution. The 
tanning may also be carried out in the paddle. 

Vegetable-tanned Goatskins. At the present time 
practically all goatskins are tanned by the tw r o-bath chrome 
process. For certain kinds of fancy morocco leather, however, 
sumac or other vegetable tanning material is employed. The 
bating of goat skins is more difficult than other pelts and a more 
active substance has to be employed. 

CHROME TANNAGE. The action of chromium salts upon 
hide substance was first studied by Knapp in 1858, but his in- 
vestigations led him to conclude that their application was of 



492 ELEMENTS OF INDUSTRIAL CHEMISTRY 

no practical value. Although other investigators took up the 
matter, it was not until 1884 that any really important advance 
was made. At this time Augustus Schultz patented his " two- 
bath process." In this process the skins or hides are treated 
with a solution of chromic acid, produced by the action of hydro- 
chloric acid upon sodium or potassium dichromate and afterward 
with a solution of sodium thiosulphate and hydrochloric acid. 
The hide substance takes up the chromic acid, which is sub- 
sequently converted to the basic condition by means of the 
" hypo." In 1893 Martin Dennis made a study' of the action 
of chromium salts as previously investigated by Knapp, and 
perfected a method for " one-bath tannage," on which he was 
granted numerous patents. 

Two-bath Chrome Process. While the details involved 
in the application of this process vary, yet chrome tanning is 
uniformly carried out either in a paddle or drum. Different 
kinds of leather require different percentages of the chemicals. 
In the drum tannage 6 per cent sodium or potassium dichromate 
and 3 per cent of hydrochloric acid, regulated on the weight of 
the wet skins, are dissolved in sufficient water for the proper 
handling of the stock. The skins or hides are placed in the drum 
and the chrome solution added, the drum being kept in motion. 
The hides or skins are worked in the solution until they have taken 
on a uniform yellow color which has completely struck through. 
They are now removed from the drum and freed from the super- 
fluous liquor by horsing up over night, or by putting out; the 
latter operation may be done by hand or on the machine. After 
standing for twenty-four hours the chromed stock is returned to 
the drum, and run for about one and one-half hours with a solu- 
tion of 12 per cent of sodium thiosulphate and 6 per cent of hydro- 
chloric acid. On removing from the drum the stock should 
have a blue-green color and be uniform throughout. If thor- 
oughly tanned no curling will occur when a strip is placed in boil- 
ing water. On removing from the drum the stock is horsed up 
for twenty-four hours to allow the chrome to set, neutralized by 
running for half an hour in a \ per cent sodium bicarbonate solu- 
tion, washed in running water for half an hour, horsed up, and 
allowed to drain. 

The reactions which take place in this process are represented 
in the following equation: 

Na 2 Cr 2 07+2HCl = 2NaCl+2Cr03+H20. 



LEATHER 493 

The Cr03 produced combines with the gelatine, forming a 
compound with it. The sodium thiosulphate now acts as a reduc- 
ing agent upon the chromic oxide, converting it from the acid to 
the basic condition, the reaction taking place in two stages: 

1. 2Cr03+6HCl+3Na2S203 = 3Na 2 S04+3S+Cr2Cl6+3H 2 0. 

2. Cr2Cl6+Na2S203+H 2 = Cr 2 (OH) 2 Cl4+S02+S+2NaCl. 

The basic chloride of chromium held by the fiber is probably 
converted to Cr 2 (OH)6 by the action of the sodium bicarbonate 
used in washing. 

ONE-BATH CHROME. In this process the skins or hides, 
after coming from the puer, are washed in running water and run 
in a pickle for about one hour. The pickle is made by dissolving 
8 lbs. of salt and 2 lbs. of sulphate of aluminium in a small amount 
of water, adding 1 lb. of sulphuric acid, and making up to a den- 
sity of 40 Bk. The object of this treatment is to neutralize any 
alkalinity of the puer or lime that may remain, and to ensure the 
stock being in an acid condition before it enters the tan.. The 
pickled skins are placed in the drum, the door closed, and one-third 
of the chrome solution introduced while the drum is in motion. 
At the end of fifteen minutes another third is added, and in thirty 
minutes the remainder. One-half hour after the last portion has 
been added \ per cent of sodium bicarbonate in solution is intro- 
duced, and the stock run for fifteen minutes longer. The hides 
or skins are then removed from the drum, horsed up over night, 
neutralized with sodium bicarbonate, thoroughly washed, horsed 
up again and allowed to drain. 

Chrome tannage by either of the processes given above may 
also be carried out in the paddle, but in this case the time of 
treatment is somewhat longer. The advantage of the paddle 
tannage is that a smoother grain is obtained with less danger of 
" pipey " leather. 

ALUM TANNAGE. This process is employed especially for 
white kid, glove and light-colored leather. 

OIL TANNAGE. The oldest tanning method of which we 
have any record was that in which the oil, fat and brains of animals 
were used to preserve the pelts in a soft and non-putrescible 
condition. The method as at present applied consists in kneading 
the goods in contact with certain oils and soft fats. As the fibers 
slowly dry the fats are worked in between them by means of the 
mechanical treatment which the goods undergo in the stocks. 



494 ELEMENTS OF INDUSTRIAL CHEMISTRY 

Each fiber is, therefore, separated from its neighbor in a non- 
adherent condition, and at the same time is surrounded by a 
waterproofing material. Not only are the fibers surrounded by 
the oil, but at the same time a vigorous oxidation occurs, resulting 
in the formation of aldehydes and other insoluble oxidation 
products. The aldehydes produced, by virtue of their chemical 
activity, unite with the hide fiber, while the insoluble products 
coat the fibers mechanically. Oil tannage is used in the manu- 
facture of chamois, buff, and buck leathers. 

ALDEHYDE TANNAGE. The use of formaldehyde as a tanning 
material has recently been brought to the attention of the tanner 
but as yet it has not become widely employed. The leather ob- 
tained by this process resembles buff leather. It is very white, 
however, and needs no bleaching. The future of this method 
remains to be seen. 

Finishing of Dressing Leather. After the leather is 
tanned by any of the methods given above it must be finished in 
such a manner as to meet the requirements of the various pur- 
poses for which it is to be used. Only a few of the most important 
operations in the finishing of leather will be given. 

Soaking. On removing the dried goods from the boards or 
drying room they are dipped in water at a temperature of 110° F. 
and placed in piles or horsed up for some hours until evenly wet 
through or sammied. The goods may also be sammied by dipping 
in warm water and then covering with damp sawdust. While 
still another method is to steam the stock gently and run in a 
drum for a short time. 

Shaving. The object of this operation is to bring the leather 
to uniform thickness, and may be done by hand or by means of 
the shaving machine. 

Splitting. This operation has replaced shaving to quite an 
extent, especially for side leather, which is now almost uniformly 
split out of the limes. In this process the leather is sliced parallel 
to the grain surface, so that the split portions have the same area 
as the original leather. Among the numerous types of splitting 
machines in use the " band-knife " type is the most popular. The 
machine consists of an endless double-beveled knife which passes 
around two pulley wheels, one of which is attached to power. 
The sammied leather is pushed toward the knife, grain upward, by 
two feed rollers; the grain split passing over the knife and the 
flesh split under it. The thickness of the split can be varied 
from one-sixteenth of an inch up to the thickness of the hide, so 



LEATHER 495 

that in some cases it is possible to obtain as many as five good 
splits from one hide. 

Fat-liquoring. This process differs from stuffing in that emul- 
sions of various oils as well as emulsions of soap and oils are em- 
ployed in place of the heavy fats. In recent years the use of 
soluble oils (sulphonated oils) has become common. The term 
fat-liquoring is usually applied to the light kinds of leather, while 
stuffing is applied to heavy leather. 

Coloring. The dyeing of leather has been greatly modified 
within recent years owing to the introduction of coal-tar colors, 
although for several shades the old vegetable colors are still in use. 

Glazing. To obtain leather with a high finish it is given a 
coat of egg albumen, blood albumen, or shellac, and then finished 
on the glazing jack. 

PATENT LEATHER. This kind of leather is made by varnish- 
ing ordinary leather. The usual method is to first degrease the 
tanned stock. It is then given a daub coat of boiled linseed oil 
and lampblack, thinned to the proper consistency with naphtha. 
The excess of the coating is removed with the slicker and a mix- 
ture of lineseed oil and guncotton applied. The hides are then 
baked and sunned, and rubbed down with pumice stone. Another 
coat of the linseed-oil varnish with pyroxylene is applied, baked, 
sunned and rubbed. Coloring matter is usually added to the 
varnish and sometimes several coats are applied. 



INDEX 



Absinthe, 427 
Absolutes, 342, 348 
Absorption system, 28 
Acacia, 366 
Acacia odors, 357 
Acetate of lime, 285 
Acetates, crude, 284 
Acetic acid, 288 
Acetone, 289 
Acetylene, 246 
Acid, cinnamic, 347 

carbolic, 257 

colors, 455 

eggs, 76 

sludge, 269 
Acker process, 121 
Agar-agar, 366 
Aldehyde tannage, 494 
Alkali earths, 195 
Alkali metals, 195 
Alkaline starches, 399 
All-oil water gas, 243 
Allspice oil, 360 
Almond oil, 299 
Alum, 108 

ammonia, 108 

potash, 108 

soda, 108 
Alum tannage, 493 
Aluminium, 106 

acetate, 106 

chloride, 106 

hydroxide, 107 

nitride, 107 

oxide, 106 

sulphate, 107 
Amalgamater, 332 
Amber, 362 
Ambergris, 346 
American sienna, 216 
American whiskey, 424 



American zinc oxide, 214 
Ammonia, 108 
Ammonia liquor, 238 
Ammonia soda process, 164 
Ammonium alum, 108 
Ammonium carbonate, 109 
Ammonium chloride, 110 
Ammonium nitrate, 110 
Ammonium sulphate, 110 
Amorphous phosphorus, 155 
Amygdalin, 353 
Aniline black, 458 
Animal fats, 309 
Animal fibers, 429, 430 
Animal oils, 300 
Anime, 363 
Anise oil, 353 
Anisette, 428 
Anthracene, 260 
Anthracite coal, 253 
Anti-freezing solution, 119 
Antimony, 110 

fluoride, 110 
Apatite, 115 
Apricot brandy, 427 
Aqua ammonia, 109 
Aqua fortis, 92 
Aquivit, 428 
Arsenic sulphide, 485 
Arazym, 486 
Argon, 111 
Arrack, 426 
Arsenate of soda, 111 
Arsenic, 111 

acid, 111 

trioxide, 111 
Arsenical pyrites, 111 
Arsenious oxide, 111 
Artificial fibers, 429 
Artificial graphite, 118 
Artificial silk, 446 



497 



498 



INDEX 



Asbestine, 215 
Asbestos, 146 
Asphalt, 275 
Asphaltene, 275 
Asphaltic base, 274 
Aubepine, 351 
Azo colors, 456 
Azotin, 220 
Azurite, 134 

Bag filtration, 391 
Bay liquor, 404 
Barley, 406 
Baking Japan, 379 
Baking powders, 165 
Ball clay, 187 
Ball mill, 8 
Balsam, 347 
Balsam, Peru, 347 
Barium, 111 

carbonate, 112 

chloride, 112 

hydroxide, 112 

nitrate, 112 

oxide, 111 

peroxide, 111 

sulphate, 112, 215, 217 
Barytes, 111, 215 
Basic colors, 454 
Bates, chemical, 488 
Bates, patent, 487 
Bating, 486 
Bauxite, 108 
Bayberry wax, 315 
Bay oil, 354 
Beater engine, 460 
Beef tallow, 310 
Bee-hive oven, 55 
Beer, 406 

carbonizing of, 413 

clarification of, 413 

fining of, 413 

filtration of, 414 

storage of, 412 

tanking of, 412 
Beeswax, 316 
Beet sugar, 387 
Belgian slag, 227 
Belt dressings, 320 
Belt leather, 489 

bleaching of, 490 

stuffing of, 490 



Benedictine, 427 
Benzaldehyde, 352 
Benzoin, 346, 347 
Benzol, 254 
Bergamot oil, 354 
Birch oil, 351 
Bismuth, 112 

nitrate, 112 
Bitter almond oil, 352 
Bittern, 167 
Bituminous coal, 52 
Black ash, 162 

lixiviation of, 163 
Black iron, 143 
Black oil, 320 
Black powder, 470 

process of manufacture, 471 

raw materials for, 470 
Black tung oil, 294 
Blast furnace, 140, 141 
Blast furnace tar, 248 
Blau gas, 245 
Bleaching powder, 131 
Blood, 220 
Blubber oils, 303 
Blue vitriol, 135 
Boiled laundry soaps, 323 
Boiled oil, 380 
Boiled toilet soaps, 332 
Boiler compounds, 34 
Boiler troubles, 33 
Boiler water, 31 
Boiling oils, 380 
Boiling out, 441 
Boussingault-Brin process, 152 
Borax, 113 
Bone, 227 

Bone phosphate, 227 
Boric acid, 113 
Boron, 113 
Bottles, 200 
Brandy, 425 
Breakers, 398 
Breaking, 372 
Brewing, 406 
Brewing materials, 407 
Brick clays, 188 
Bricks, building, 190 

burning of, 192 

drying of, 191 

molding of, 191 
Brimstone, 174 



INDEX 



499 



Briquettes, 53 
British gum, 404 
Bromine, 113 
Building bricks, 190 
Burgundy pitch, 63 
Burners, fines, 70 

lump, 69 

O'Brien, 70, 71 

Wedge, 70, 72 
Burnt ochre, 216 
Butter fat, 312 
Butter substitute, 312 
By-product ovens, 55, 56, 57, 58 

Cadmium, 114 

sulphide, 115 

yellow, 115 
Caesium, 115 
Calcination, 16 
Calcium, 115 

carbide, 115, 151 

carbonate, 118 

chloride, 119 

cyanamide, 222 

fluoride, 119 

hydroxide, 119 

hypochlorite, 130 

nitrate, 119 

oxide, 118, 195 

sulphate, 119 

sulphide, 119 
Calf skins, 491 
Calomel, 148 
Calorimeter, 50 
Camphor, 352 
Camphor oil, 352 
Canauga oil, 350 
Candelella wax, 315 
Caoutchouc, 369 
Carbide furnace, 115, 116 
Carbolic acid, 257 
Carbolinium avenarius, 261 
Carbon, 119 

black, 217 

disulphide, 120 

tetrachloride, 120 
Carborundum, 117 
Carborundum furnace, 117 
Carnalite, 146 
Carnauba wax, 314 
Car oils, 320 
Carter process white lead, 209 



Cassia oil, 361 
Cassia odors, 357 
Castile soap, 335 
Castner cell, 123 
Castner-Kellner process, 123 
Castor oil, 298 
Castorium, 347 
Catalytic action, 81 
Caustic potash, 157 
Caustic soda, 160 
Cedar oil, 358 
Cellulose, 50 
Cement, grappier, 180 

La Farge, 180 

natural, 180 

Portland, 180 
Centrifugal machine, 13 
Centrifugal separators, 73 
Centrifugals, 386 
Ceramics, 177 
Cereals, 408 
Cerite, 121 
Cerium, 121 
Chalcopyrite, 134 
Chalk, 115 
Chamber system, 74, 75 

reactions in, 74 
Charcoal, 53, 217 

kiln, 278 

pit, 277 
Chardonnet silk, 446 
Char filtration, 392 
Chartreuse, 427 
Chaser, 5 
Chemiking, 442 
Cherry brandy, 427 
Chili saltpeter, 195 
Chinese wax, 315 
Chinese wood oil, 294 
Chipper, 332 
Chlorine, 121 

chemical properties of, 126 

process of manufacture, 126 
Chrome alum, 133 
Chrome green, 216, 453 
Chrome oxide, 216 
Chrome steel, 132 
Chrome tannage, 491 
Chrome yellow, 216, 453 
Chromic acid, 133 
Chromic anhydride, 132 
Chromite, 132 



500 



INDEX 



Chromium, 132 

acetate, 132 

chloride, 132 

hydroxide, 132 

oxide, 132 

sulphate, 132 
Cinnabar, 148 
Cinnamon oil, 361 
Cinnamic acid, 347 
Circulating system, 76 
Citral, 356 
Citronella oil, 355 
Citronellol, 348 
Citrus oil, 354 
Civet, 346 
Clays, 108, 187 

uses of, 190 

weathering of, 190 
Clove oil, 360 
Coal gas, 63 

manufacture of, 231 
Coal tar, 247 
Cobalt, 134 

blue, 216 
Cochineal, 452 
Cocoa butter, 308 
Cocoanut oil, 308 
Cod liver oil, 302 
Coffey still, 23, 24 
Cognac, 425 
Cohobation, 353 
Coke, 54, 55 
Cold process soap, 335 
Cold water softening, 44 
Colemanite, 113 
Colophony, 363 
Color lakes, 456 
Colored glass, 200 
Columbium, 134, 174 
Column stills, 23 
Colza oil, 298 
Commercial glucose, 408 
Common process, 97 
Compressor oils, 321 
Compression system, 28 
Concentrated tankage, 224 
Condensers, 235 
Contact plant, 83 

construction of, 82 

process, 81 
Continuous kilns, 178 
Conveying gases, 27 



Conveying liquids, 26 
Conveying solids, 24 
Coolers, 270 
Copal, 364, 374 
Copra, 308 
Copper, 134 
Copperas, 143 

oxide, 134 

sulphate, 135 
Corium, 481 
Corn, 408 
Corn oil, 296 
Corrosion, 32 
Corrosive sublimate, 148 
Cotton, 436 

bleaching of, 438 

boiling out, 438 

physical properties of, 437 
Cottonseed oil, 297 
Cottonseed stearin, 307 
Cracking, 268 
Crank case oil, 321 
Creelin, 258 
Creme de cocoa, 428 
Creme de menthe, 428 
Creme de roses, 428 
Creme de vanilla, 428 
Creme de yvette, 428 
Creosote oil, 255 
Creosote salts, 258 
Cresol, 257 
Cresylic acid, 257 
Croton oil, 298 
Crown glass, 200 
Crude distillation, 340 
Crude oil, 60 
Crude tar, 286 
Crusher, 1, 2 
Crushing rolls, 2, 3, 4 
Crutcher, 327 
Crutching, 327 
Cryolite, 108 
Cryolite process, 165 
Crystallization, 15 

fractional, 16 
Cuba wood, 453 
Cumarine, 350 
Curacao, 428 
Cus-cus, 356 
Cutch, 453 
Cut glass, 201 
Cutting, 328 



INDEX 



501 



Cyanide, 150, 222 
Cylinder oil, 319 
Cylinder stocks, 373 

Dammar, 364 
Dammar varnish, 371 
Dark malts, 409 
Dark varnish, 378 
Day tank, 197 
Deacon process, 128 
Decorated glass, 201 
Depiiation, 484 
Dermiforma, 488 
Dessert wines, 421 
Detonators, 479 
Developing agents, 449 
Developing colors, 457 
Devine dryer, 14 
Dextrin, 44, 395 
Diaphragm process, 125 
Diaspore, 108 
Direct colors, 455 
Direct saponification, 325 
Disintegrator. 6 
Distillation, 22, 47 

crude, 340 

modern, 344 

steam, 273 

wood, 277 
Distilled liquor, 423 
Dolomite, 146 
Dolphin oil, 305 
Dragon's blood, 364, 365 
Drenching, 488 
Dry colors, 218 
Dry fish scrap, 222 
Drving, 14 
Drying oils, 293 
Dust prevention, 73 
Dutch process white lead, 206 
Dyeing, 447 

assistants, 449 
DyestufTs, 447 

classification of, 449 

natural, 450 
Dynamite, 476, 477 

Earth wax, 275 
Eau de Javelle, 130 
Economizers, 47 
Eggs, 76 



Egg oil, 306 
Electric iron, 142 , 
Electric steel, 142 
Electrolytic oxygen, 151 
Elemi, 365 
Elevating liquids, 26 
Enfleurage process, 341 
Engine oil, 318 
Enriching oils, 243 
Epidermis, 481 
Epsom salts, 147 
Erbium, 135 
Essential oils, 340 
Eucalyptus oils, 359 
Evaporation, 18 

by direct heat, 18 

by indirect heat, 18 

spontaneous, 18 

under reduced pressure, 19 
Evaporator, Lillie, 21 

Yaryan, 20 
Exhauster, 237 
Explosives, 420 — 
Expressed oils, 340 
Extraction, 15 

Fat, butter, 312 
Fats, 290, 311 

animal, 309 

classification of, 290 

constitution of, 292 

vegetable, 306 
Fatty oils, 290 
Feed water heaters, 41 
Feed water heating, 46 
Feldspar, 108 
Fermentation, 411 
Ferric chloride, 144 
Ferric oxide, 144 
Ferric nitrate, 144 
Ferric sulphate, 144 
Ferro-alloys, 142 
Ferrous acetate, 143 
Ferrous sulphate, 143 
Ferrous sulphide, 144 
Fertilizers. 219 

calculations 228 

expression of formula 220 

market quotations, 220 

materials, for, 219 

stimulants, 219 

terms used in analysis, 219 



502 



INDEX 



Filter, bag, 12 

press, 12 

ribbed, 11 

suction, 12 

Sweetland, 12, 13 
Filtration, 11 

rapid sand, 42, 44 

sand, 40 

slow sand, 42, 44 
Fines burners, 70 
Fining of beer, 413 
Fire clays, 188 
Fire bricks, 192 
Fish oils, 301 
Fish scrap, dry, 222 
Fixation of nitrogen, 150 
Fixatives, 344 
Fixing agents, 448 
Flake naphthalene, 259 
Flameless explosives, 478 
Flash light powder, 146 
Flattening out, 325 
Fleshing, 484 
Floating soaps, 335 
Floor malting, 406 
Flour of sulphur, 174 
Flow box, 461 
Flower concretes, 342 
Flower perfumes, 348 
Flower pomade, 341 
Flowers of sulphur, 173 
Fluffy powders, 332 
Fluorspar, 115, 119 
Fluorine, 135 
Foaming, 32 
Foots, 273 

Fourdrinier machine, 462 
Fractional crystallization, 16 
Frames, 328 
Framing, 328 
Frasch process, 173 
French process zinc oxide, 214 
French zinc oxide, 214 
Fuels, 49 

constituents of, 49 

definition of, 49 

solid, 50 
Fuller-Lehigh pulverizer, 8 
Fulminants, 479 
Furnaces, carbide, 116 

carborundum, 117 

graphite, 118 



Furnaces, muffle, 17 

pot, 197 

reverberatory, 16 

revolving, 17 

Siemens regenerative, 62 

sulphur, 68 

tank, 197 
Fustic, 453 

Gadolinium, 135 
Galena, 144, 146 
Galium, 135 
Galvanized iron, 176 
Gambier, 453 
Gardena oil, 350 
Gas engine oils, 319 
Gaseous fuels, 61 
Gas light mantles, 144, 174 
Gasolene gas, 246 
Gay-Lussac tower, 66, 67 

reactions in, 76 
Gelatin dynamite, 477 
Geranium oil, 359 
Geranilql, 348 
Germanium, 135 
German silver, 149 
Germination, 406, 407 
Gin, 425 

Gingergrass oil, 356 
Glass, 194 

annealing of, 202 

blowing, 199 

casting of, 198 

coloring materials for, 196 

cut, 201 

decorated, 201 

heavy metals in, 195 

machine made, 199 

melting process, 198 

pressing of, 199 
Glauber's salt, 177 
Glazer, 199 
Glory hole, 199 
Glost kiln, 193 
Glover tower, 66, 67, 74 

reactions in, 74 
Glucinium, 135 
Glucose, 395, 400 

manufacture of, 402 
Gluten, 395, 405 
Gluten feed, 398 
Glycerine, 336 



INDEX 



503 



Glycerine, purification of, 339 

saponification, crude, 338 

soap lye, crude, 337 

sources of, 336 
Goat skins, 491 
Gold, 135 

Golds chmidt process, 132 
Graining, 325 
Grapes, 414 

crushing of, 415 

pressing, 415 

stemming of, 415 
Graphite, 217 

artificial, 118 

furnaces, 118 
Grappier cements, 180 
Grass oils, 355 
Gray lime, 285 
Gray wash, 441 
Greases,_ 320 
Green vitriol, 143 
Griffin mill, 9 
Grinding, 107 
Guaiac, 365 
Guano, 221 
Gumbo clays, 189 
Gum resins, 362, 366 
Gums, 362 

benzoin, 316 

labdanum, 347 
Gypsum, 115, 217 

Haddock liver oil, 303 

Hsematin, 451 

Half boiled soaps, 334 

Hard-wood distillation, 282 

Harness, leather, 489 

Hawthorn, 351 

Heat of combustion, 49 

Heavy oil, 255 

Heavy spar, 111 

Heliotrope flower, 352 

Heliotropine, 352 

Helium, 136 

Hemp, 445 

Hemp seed oil, 295 

Herb oils, 360 

Hides, 482 

soaking of, 483 
HoUander, 460 
Hollow brick, 192 
Hollow structural materials, 192 



Hollow ware, 200 
Hops, 409 

Horizontal retorts, 231 
Horn silver, 160 
Horse fats, 311 
Horse's foot oil. 305 
Hydrargallite, i08 
Hydrated lime, 179 
Hydraulic lime, 180 
Hydraulic main, 235 
Hydrochloric acid, 137 

purification of, 138 

uses of, 138 
Hydrogen peroxide, 136 
Hypochlorites, 129 
Hydroxy benzene, 257 

Ice colors, 457 
Iceland moss, 366 
Ice machine oil, 321 
Illuminating gas, 231 
Illuminating oils, 367 
Incense, 347 
Inclined retort, 232 
Incrustation, 31 
India-rubber, 369 
Indian red, 216 
Indigo, 450, 457 
Indigo extracts, 451 
Indium, 138 
Infusorial earth, 217 
Ink grinding, 10 
Insoluble shellac, 371 
Intermittent kilns, 17 
Iodine, 138 
Iodoform, 139 
Ionol, 356 
Ionone, 356 
Iovionol, 356 
Iralol, 356 
Iridium, 139 
Irish moss, 366 
Irish whiskey, 424 
Iron, 139 
Iron buff, 454 
Iron liquor, 143 
Iron ores, 139 

Japan dryers, 379 
Japan wax, 314 
Jasmine blossom, 350 
Jasmine flower, 350 



504 



INDEX 



Jaw crusher, 1, 2 
Jordan engine, 461 
Juniper oil, 358 
Jute, 445 

Kainite, 146, 147 

Kaolin, 108, 187 

Kauri, 365 

Kestner lifts, 76, 77 

Kestner stills, 81 

Kettles, steam-jacketed, 18, 19 

Khaki, 454 

Kiei;, 442 

Kieserite, 146, 147 

Kiln, rotary, 183 

Kilning, 407 

Kilns, 18 

continuous, 178 

down draft, 192 

intermittent, 177 

ring, 179 

up draft, 192 

vertical, 178 
Kips, 483 

Kopper coke oven, 58, 59 
Kornbrannt wein, 425 
Krausen, 411 
Krausening, 413 
Krypton, 144 
Kummel, 428 
Kusa, 356 

Labdanum, 347 
Lac dye, 368 
Lac sulphur, 174 
Lacquer, 372 
La Farge cement, 180 
Lakes, 218 
Lamp black, 217 
Lanolin, 316 
Lanthanum, 144 
Lard, 312 
Lard oil, 306 
Lavender oil, 359 
Lead, 144 

carbonate, 145 

chloride, 145 

dioxide, 145 

in oil, 211 

nitrate, 145 

oxide, 145 

plaster, 336 



Lead, suboxide, 145 

sulphate, 146 

sulphide, 146 
Leather, 481 
Leblanc process, 161 
Lehr, 198, 202 
Lemongrass oil, 356 
Lemon oil, 354 
Leveling agents, 449 
Levigation, 11 
Light oil, 254 
Lignite, 51 
Lignocellulose, 50 
Lilac flower oils, 359 
Lillie evaporator, 21 
Lime, 177 
Lime oil, 441 
Lime stone, 115, 183 
Lime water, 119 
Liming, 484 
Linde process, 151, 152 
Linoxyn, 374 
Linseed oil, 294 

weight of, 373 
Liquid air, 152 
Liquid air, oxygen from, 152 
Liquid fuels, 60 
Liquid soaps, 334 
Liquid waxes, 313 
Liquor, 406 
Litharge, 145 
Lithographic oil, 380 
Lithopone, 214 
Liver oils, 302 
Lixiviation, 15 
Lock boxes, 266 
Logwood, 451 
Loom oil, 318 
Lowe apparatus, 240 

fuel used, 242 

operation of, 241 
Lubricating oils, 270, 317 

choice of, 317 
Luminous paints, 119 
Lump burners, 69 

Macerating process, 341 
Madder, 452 
Magnesite, 146 
Magnesium, 146 

cement, 146 

chloride, 146 



INDEX 



505 



Magnesium, oxide, 146 

peroxide, 146 

sulphate, 147 
Maize oil, 296 
Malachite, 134 
Malt, 408 

properties of, 408 
Malting, 406 

operations, 406 
Manganese, 147 

dioxide, 147 

sulphate, 147 
Maraschino, 427 
Marble, 115 
Marine animal oils, 301 
Marl, 183 
Mashing, 409 
Massecuite, 386 
Mastic, 365 \ 
Mastic varnish, 371 
Matheson process white lead, 211 
Mechanical process, 464 
Meiler, 278 
Melting resins, 373 
Menhaden oil, 301* 
Mercuric chloride, 148 
Mercuric oxide, 148 
Mercurous chloride, 148 
Mercurous nitrate, 148 
Mercurous oxide, 148 
Mercurous sulphate, 148 
Mercury, 148 

fulminate, 479 
Meta cresol, 258 
Metallic soap, 336 
Milk of lime, 119 
Milling, 333 

Milling machine oils, 321 
Mills, ball, 8 

Griffin, 9 

pebble, 9 

roller, 10 

soap, 333 

tube, 10 
Minium, 145 
Minor animal fibers, 434 
Mimosa, 357 
Mineral black, 217 
Mineral dyestuffs, 453 
Mineral fibers, 429 
Mispickel, 111 
Mixing glucose, 404 



Molding, 191 
Molybdenite, 149 
Molybdenum, 149 
Monazite sands, 174 
Monkey pots, 198 
Montan wax, 316 
Montejus, 102 
Mordant colors, 456 
Mordants, 448 
Mortar, 179 
Mottled soaps, 335 
Movement of gases, 77 
Muffle furnace, 17 
Multiple effect system, 20 
Musk, 345 

synthetic, 346 
Mutton tallow, 311 
Myrrh, 347 
Myrtle wax, 315 

Naphtha, 267 
Naphthalene, 258 
Natural cement, 180 
Natural dyestuffs, 450 
Natural gas, 64 
Natural waters, 30 

composition of, 30 
Neat's-foot oil, 306 
Neodymium, 149 
Neon, 149 
Neovinol, 356 
Neroli, 349 

petals, 349 
Neutral oils, 321 
Neutralize^ 402 
New mown hay, 351 
Nickel, 149 

coins, 149 

matte, 149 

sulphate, 149 
Nigre, 327 
Nitrate of iron, 147 
Nitric acid, 91 

charging of, 99 

condensation of, 100, 101 

distillation of, 99 

manufacture of, 92 

occurrence, 92 

properties of, 91 
Nitro-cellulose, 472, 473 

purification of, 474 

raw materials for, 472 



506 



INDEX 



Nitrogen, 149 

fixation of, 150 
Nitro-glycerine, 476 
Nitro-starch, 476 
Noils, 432 

Non-drying oils, 299 
Numerical standard, 35 

O'Brien burner, 70, 71 

Ochre, 217 

Oil, allspice, 360 

almond, 299 

anise, 353 

bay, 354 

bergamot, 354 

birch, 351 

bitter almond, 352 

black tung, 294 

camphor, 352 

canauga, 350 

cassia, 361 

castor, 298 

cedar, 358 

Chinese wood, 294 

cinnamon, 361 

citronella, 355 

citrus, 354 

clove, 360 

cocoanut, 308 

cod liver, 302 

colza, 298 

corn, 296 

cotton seed, 297 

creosote, 255 

croton, 298 

dag, 321 

dolphin, 305 

egg, 306 

engine, 318 

geranium, 359 

gingergrass, 356 

haddock liver, 303 

heavy, 255 

hemp seed, 295 

horse's foot, 305 

juniper, 358 

lard, 306 

lavender, 359 

lemon, 354 

lemongrass, 356 

linseed, 294 

loom, 318 



Oil, lubricating, 270 
maize, 296 
menhaden, 301 
neat's-foot, 306 
oleo, 313 
olive, 299 
olive kernel, 300 
orange, 355 
orris, 357 
palm, 307 
palm kernel, 308 
palma-rosa, 355 
patchouly, 349 
peach kernel, 299 
peanut, 299 
pelargonium, 359 
peppermint, 361 
perilla, 293 
petitgrain, 350 
pimento, 360 
poppy, 295 
porpoise, 305 
pumpkin seed, 296 
rape, 298 
rose, 348 
salad, 297 
salmon, 302 
sandalwood, 357 
sardine, 302 
sassafras, 352 
sea elephant, 305 
seal, 303 
sesame, 297 
shark liver, 303 
sheep's foot, 305 
soja bean, 295 
soluble, 298 
sperm, 313 
spindle, 318 
steam reduced, 271 
sunflower, 295 
tallow, 306 
tannage, 493 
tobacco seed, 295 
tung, 294 
turkey red, 298 
vetiver, 356 
watch, 318 
whale, 304 
white tung, 294 
wintergreen, 351 
ylang-ylang, 350 



INDEX 



507 



Oil gas, 64 
Oil gas tar, 248 
Oilless bearings, 321 
Oils, 290 

animal, 300 

black, 320 

blubber, 303 

car, 320 

compressor, 321 

drying, 293 

eucalyptus, 359 

fatty, 290 

fish, 301 

gas engine, 319 

grass, 355 

herb, 361 

ice machine, 321 

illuminating, 267 

lilac flower, 359 

liver, 302 

lubricating, 357 

marine animal, 301 

milling machine, 321 

neutral, 321 

non-drying, 299 

pine, 288 

screw cutting, 321 

semi-drying, 295 

soluble, 321 

spice, 361 

spindle, 273 

stainless, 322 

tar, 287 

terrestrial animal, 305 

transformer, 322 

turbine, 322 

vegetable, 293 

well, 320 
Oleo oil, 313 

Oleo resinous varnishes, 372 
Oleo resins, 366 
Olive kernel oil, 300 
Olive oil, 299 
Optical glass, 200 
Orange flower, 349 
Orange mineral, 215 
Orange oil, 355 
Organic dyestuffs, 454 

classification of, 454 
Oropon, 487 
Orpiment, 111 
Orris oil, 357 



Orris root, 357 
Ortho cresol, 257 
Osmium, 151 

Otto-Hoffman oven, 56, 57 
Otto of roses, 348 
Oxygen, 151 

electrolytic, 151 

from liquid air, 152 
Ozokerite, 275 
Ozone, 152 

apparatus for, 153 

machines, 153 
Oven gas tar, 247 

Paint clays, 189 
Paint, grinding of, 7 

vehicles, 217 
Pale varnish, 378 
Palladium, 154 
Palm kernel oil, 308 
Palm oil, 307 
Palm wine, 426 
Palma rosa oil, 355 
Paper, 459 

clays, 189 

raw materials for, 459 
Para cresol, 258 
Paraffin base, 262 
Paraffin wax, 272 
Paste colors, 218 
Patchouly oil, 349 
Patent bate, 495 
Paulie's process, 163 
Paving brick clays, 189 
Peach brandy, 427 
Peach kernel oil, 299 
Peanut oil, 299 
Peat, 50 
Peat filler, 228 
Pebble mills, 9 
Pelargonium, 359 
Pelts, classification of, 482 
Peppermint oil, 361 
Perfumes, constitution of, 342 

materials, 343 
PeriUa oil, 293 
Permanent vermilion, 216 
Permutit, 45 
Peroxides, 136 
Persian berries, 453 
Petitgrain oil, 350 



508 



INDEX 



Petrolene, 275 
Petroleum, 60, 262 

constitution of, 262 

locality of, 263 

origin of, 262 

production of, 264 

refining of, 264 

sulphur content, 269 
Phenol, 257 

Phosphate, crude stock, 225 
Phosphate rock, 225 
Phosphoric acid, 155, 225 
Phosphorus, 154 
Photographic dry plates, 160 
Phthalic anhydride color, 455 
Pickling, 138, 488 
Picric acid, 478 
Pig lead, 145 
Pigments, 203 

applications of, 203 

definitions of, 203 

grinding, 7 
Pimento oil, 360 
Pine oil, 288 
Pintsch gas, 245 
Pintsch gas tar, 248 
Pipe clay, 189 
Pitch blende, 176 
Plaster of Paris, 119, 186 
Plate glass, 198 
Platinum, 155 

stills, 80 
Plodder, 334 
Plodding, 334 
Poly sulphate, 95 
Pomades, 348 
Poppy oil, 295 
Porcelain, 193 
Porpoise oil, 305 
Portland cement, 180 

clays, 189 
Pot clays, 189 
Pot furnaces, 197 
Pot stills, 98 
Pots, monkey, 198 
Potable water, 37 
Potash, 227 
alum, 108 
crude stock, 227 
Potassium, 155 

carbonate, 156. 195 
chlorate, 156 



Potassium, chloride, 156 

cyanide, 156 

dichromate, 133 

ferri-cyanide, 157 

ferro-cyanide, 157 

hydroxide, 157 

nitrate, 157, 195 

permanganate, 147 

titanium oxalate, 175 
Potato starch, 400 
Pottery, 193 
Praseodymium, 157 
Prentice process, 93 
Press filter, 12 
Pressing, 328 
Primers, 479 
Prince's mineral, 217 
Printing textile, 447 
Process of nitration, 473 
Producer gas, 61 
Producer gas tar, 248 
Prune brandy, 427 
Prunty, 200 
Prussian blue, 216, 453 
Puering, 487, 488 
Pug mills, 191 
Pulp colors, 218 
Pulverizer, Fuller-Lehigh, 8 
Pumpkin seed oil, 296 
Purification of water, 33, 40 
Purifier, 238 
Pyrites, burning of, 68 
Pyrolusites, 147 
Pyroxylin varnish, 372 

Queretion bark, 453 
Quicksilver vermilion, 215 

Racking, 414 

Rag boilers, 459 

Rag paper, 459 

Ramie, 445 

Rape oil, 298 

Rapid sand nitration, 42, 44 

Realgar, 111 

Reduced oils, 320 

Red lead, 215 

Red precipitate, 148 

Red phosphorus, 155 

Red wines, 420 

Red woods, 452 

Refrigeration, 27 



INDEX 



509 



Remedies for oven troubles, 33 
Resinous wood distillation, 282 
Resins, 362, 373 
Retort clays, 189 
Retort gas tar, 247 
Retorts, 279 

for wood distillation, 279 
Reverberatory furnace, 16 
Revolving furnace, 17 
Rhodium, 158 
Ribbed filter, 11 
Ring kilns, 179 
Ring nits, 191 
Rippling, 443 
Rodinol, 348 
Rodium, 167 
Roller mills, 4, 10 
Rolls, crushing, 2, 3, 4 
Rose oil, 348 
Rosin, 363, 378 

saponification, 325 
Rotaiy fine crusher, 3, 5 
Rotary kiln, 183 
Rowley process white lead, 212 
Rubbing varnish, 378 
Rubidium, 158 
Rubv glass, 201 
Rum, 426 
Ruthinium, 158 

Safetv powders, 478 
Safrof, 352 
dagger clavs, 189 
Salad oil, 297 
Salmon oil, 302 
Salt, 165 

denatured, 169 

evaporation of brine, 168 

properties of, 166 

theory of deposits, 166 

uses of, 168 

working of deposits, 166 
Salt cake, 162, 169 

conversion of, 162 

preparation of, 162 
Saltpeter, 470 
Salts of tartar, 156 
Samarium, 158 
Sandalwood oil, 357 
Sandarac, 366 
Sandarac varnish, 371 
Sand filtration, 40 



Santalol, 358 
Saponification, 337 

crude, 331 
Saponified rosin, 326 
Sardine oil, 302 
Sassafras oil, 352 
Scale, formation of, 31 
Scandium, 158 
Schnapps, 425 
Scotch whiskey, 424 
Scouring powders, 232 
Scouring soaps, 332 
Screw cutting oils, 321 
Scrubber, 237 
Sea elephant oil, 305 
Seal oil, 303 
Seaweed, 138 
Second change, 325 
Second rosin change, 326 
Sedimentation, 11 
Seed lac, 368 
Selenium, 158 
Semet-Solvey ovens, 57, 58 
Semi-drying oils, 295 
Semi-water gas, 61 
Serpentine, 146 
Sesame oil, 297 
Settling, 327 
Sewerpipe clavs, 188 
Sha butter, 309 
Shale oil, 274 
Shark liver oil, 303 
Shaving creams, 336 
Shaving soap, 336 
Sheep's foot oil, 305 
Sheep skin, 491 
Shellac, 367, 368 

varnish, 370 

wax, 316 
Sienna, 217 

Siemens regenerative furnace, 62 
Sifting, 11 
Silica, 194, 217 

stills, 81 
Silicon, 159 
Silk, 435 

bleaching of, 436 

weighting of, 144 
Silver, 159 

bromide, 160 

chloride, 160 

iodide, 160 



510 



INDEX 



Silver, nitrate, 160 
Singeing, 441 
Sisal, 445 
Skins, 482 

structure of, 481 
Skogeland condenser 103, 104 
Slabber, 328 
Slabbing, 328 
Slack wax, 270 
Slaughterhouse tankage, 224 
Slibowitz, 426 
Slip clay, 189 

Slow sand filtration, 42, 44 
Sludge acid, 269 
Smalt, 111 
Smaltite, 111 
Smokeless powders, 475 
Soap, 323 

boiled laundry, 324 

finishing of, 326 

lye, 331 

lye crude, 331 

making, 323 

mills, 333 

powders, 331 

theory of making, 323 
Soaps, classification of, 323 
Soda process, 465 
Sodium, 16C 

alum, 108 

arsenate, 111 

bicarbonate, 165 

bisulphite, 172 

carbonate, 161, 195 

chlorate, 172 

chloride, 165 

dichromate, 134 

hydroxide, 161 

hypochlorite, 130 

nitrate, 169, 195 

peroxide, 160 

stannate, 175 

sulphate, 169 

sulphide, 172, 486 

sulphite, 171 

thiosulphate, 172 
Soft soaps, 334 
Soja bean oil, 295 
Sole leather, 489, 491 
Solid fuels, 50 
Solid waxes, 313 
Soluble oils, 298, 321 



Solvay process, 164 

Souring, 443 

Sparkling wines, 422 

Spermaceti, 316 

Sperm oil, 313 

Spice oils, 360 

Spiegel, 147 

Spindle oil, 273, 318 

Spiral feed, 10 

Spirit varnish, 370 

Spontaneous evaporation, 18 

Spuds, 270 

Stabilizers, 476 

Stainless oils, 322 

Stand oil, 380 

Starch, 395, 

classification of, 395 

drying of, 398 

manufacture of, 396 

potato, 400 

sources of, 396 

wheat, 400 
Starches, alkaline, 399 

thick boiling, 399 

thin boiling, 399 
Steam distillation, 273, 283 
Steam- jacketed kettles, 18 
Steam reduced oils, 271 
Stearin, 308 
Steel, 142 
Steel tub, 396 
Steeping, 406 
Stibnite, 110 
Stick lac, 368 
Still, pot, 98 
Stills, Kestner, 81 

silica, 81 
Stannic chloride, 175 
Stannous chloride, 175 
Stoneware, 193 
Stoneware clays, 188 
Storage batteries, 145 
Strausfurt deposits, 155, 156 
Strike pan, 385 
Stripping, 328 
Strong change, 326 
Strong water, 92 
Strontianite, 172 
Strontium, 172 

nitrate, 172 
Styrax, 347 
Sublimed white lead, 212 



INDEX 



511 



Suction filter, 12 
Sugar, 381 

crystallization, 384 

curing of, 386 

defecation process, 382 

evaporation, 383, 390 

extraction of, 387 

purging of, 386, 390 

purification of juice, 382, 389 

refining, 391 
Suint, 432 

Sulphite process, 467 
Sulphur, 172 

burning of, 67 

colors, 456 

monochloride, 174 
Sulphuric acid, 65 

concentration of, 78, 79, 80 

occurrence of, 65 

outline of process, 66 

purification of, 77 

properties of, 65 

raw materials for, 66 
Sunflower oil, 295 
Sweaters, 272 
Sweating, 484 
Sweetland filter, 13 
Sweet wines, 421 
Synthesis, 342 

Talc, 146 
Tallow, 310 

beef, 310 

mutton, 311 

oil, 306 

vegetable, 308 
Tankage, 220 
Tank furnace, 197 
Tank liquors, 163 

purification of, 163 
Tannage, vegetable, 489 
Tantalum, 174 
Tar, 248 

application of, 248 

crude wood, 286 

distillation of, 250 

extractor, 236 

oils, 287 
Target, 468 
Tellurium, 174 
Terbium, 174 
Terpineol, 358 



Terra alba, 217 
Terrestrial animal oils, 305 
Textiles, 429 

definition of, 429 

origin of, 429 
Thallium, 174 

Thenard process for white lead, 411 
Thick boiling starches, 399 
Thin boiling starches, 399 
Thessie du Motay-Marechal process, 

152 
Thomas slag, 227 
Thorium, 174 
Thulium, 175 
Tile, 192 
Tin, 175 
Titanite, 175 
Titanium, 175 
Tobacco seed oil, 295 
Toddy, 426 
Toilet powders, 336 
Toluol, 255 
Tower acid, 74 
Townsend cell, 125 
Tragacanth, 366 
Tram silk, 435 
Transformer oils, 322 
Transparent soap, 336 
Tricalcium phosphate, 225 
Trinitro toluol, 478 
Tube mills, 10 
Tung oil, 294 
Tungsten, 176 
Turbine oils, 322 
Tonka bean, 351 
Turkey red oil, 298 
Turmeric, 453 
Turpentine oil, 358 
Twitchell process, 329 

UebePs process, 94 
Ultramarine blue, 216 
Umber, 217 
Unhairing, 486 
Uraninite, 157 
Uranium, 176 

Vacuum dryer, 14, 15 
Vacuum pan, 19 
Valentiner's process, 95 
Vanadium, 176 
Vandyke brown, 217 



512 



INDEX 



Vanilla bean, 360 
Vanillene, 360 
Varnish, 370 

classes of, 370 

definition of, 370 

films, 375 

making of, 376 

nomenclature, 374 

oil, 372 

outfit, 375 

properties, 377 

thinning of, 377 
Vaseline, 274 
Vat colors, 457 
-Vegetable drying oils, 293 
Vegetable fats, 306 
Vegetable fibers, 429, 430 
Vegetable non-drying oils, 299 
Vegetable oils, 293 
Vegetable semi-drying oils, 295 
Vegetable tallow, 307 
Venetian red, 215 
Vertical kilns, 178 
Vertical retorts, 233 
Vetiver oil, 356 
Vine black, 217 
Violet odors, 357 
Vitrex, 99 
Vodka, 427 
Volatile solvents, 

Ware clays, 189 
Washing powders, 331 
Water, 30 

bacteriological qualities of, 38 

chemical qualities of, 39 

classification of, 35 

for industrial use, 37 

physical qualities of, 38 

potable, 37 

purification of, 40 

softening, 44 

uses of, 30 
Water gas, 63, 240 

all-oil, 243 

tar, 248 
Water glass, 159 
W T ater mark, 463 
Watch oil, 318 
Wax, bayberry, 315 

candella, 315 

carnauba, 314 



Wax, Chinese, 315 

earth, 275 

Japan, 314 

Montan, 316 

myrtle, 315 

paraffin, 212 

shellac, 316 

tailings, 270 
Wax wool, 316 
Waxes, 290 

classification of, 291 

liquid, 313 

solid, 314 
Wedge burners, 70, 72 
Weighting silk, 144 
Weldon process, 126 
Well oils, 320 
Wet acid, fish scrap, 224 
Wet machine, 464, 479 
Whale oil, 304 
Whiskey, 423 
White arsenic, 111 
White lead, 205 

Carter process, 209 

chemical changes, 207 

corroding of, 206 

Dutch process, 206 

grinding of, 208 

Matheson process, 211 

Mild process, 212 

Rowley process, 212 

sublimed, 212 

Thenard process, 211 
White tung oil, 294 
White waxes, 193 
White wines, 419 
Whiting, 215 
Williamson machine, 243 
Wine, 406, 414 

fermentation of, 418 

yeasts, 418 
Window glass, 199 
Wintergreen oil, 351 
Wire glass, 198 
Witherite, 111 
Wolframite, 176 
Wollastonite, 115 
Wood. 50 

alcohol, 286 

distillation, 277 
Wool, 430 

bleaching of, 433 



INDEX 



513 



Wool, chemical treatment of, 433 

grading of, 432 

grease, 431 

mechanical treatment of, 432 

scouring of, 431 

sorting of, 432 

wax, 316 
Wort, boiling, of, 410 

cooling of, 410 

pitching, 410 
Wrapping, 328 

Xenon, 176 



Xylenol, 258 

Yaryan evaporator, 20 
Yellow woods, 452 
Ylang-ylang oil, 350 
Ytterbium, 176 
Yttrium, 176 



Zinc, 176 

oxide, 176, 213, 
sulphate, 176 

Zirconium, 176 



214 



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POPE, F. G. Modern Research in Organic Chemistry. 
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Chemical Analysis. Seventh Edition, revised and en- 
larged. 8vo. cloth. 439 pp. net, $3.50 

PRESCOTT, A. B., and SULLIVAN, E. C. First Book in 
Qualitative Chemistry. For studies of water solution 
and mass action. Eleventh Edition, entirely rewritten. 
i2mo. cloth. 150 pp. net, $1.50 

PRIDEAUX, E. B. R. Problems in Physical Chemistry 
with Practical Applications. 13 diagrams. 8vo. cloth. 
323 pp. net, $2.00 

PR0ST, E. Manual of Chemical Analysis. As applied 
to the assay of fuels, ores, metals, alloys, salts, and 
other mineral products. Translated from the original 
by J. C. Smith. Illus. 8vo. cloth. 300 pp. net, $4.50 

PYNCH0N, T. R. Introduction to Chemical Physics. 
Third Edition, revised and enlarged. 269 illustrations. 
8vo. cloth. 575 pp. $3.00 

RICHARDS, W. A., and NORTH, H. B. A Manual of 
Cement Testing. For the use of engineers and chem- 
ists in colleges and in the field. 56 illustrations. 
i2mo. cloth. 147 pp. net, $1.50 

RIDEAL, S. Glue and Glue Testing. Second Edition, 
revised and enlarged. 14 illustrations. 5^4 x 8%. 
cloth. 194 pp. net, $4.00 

ROGERS, ALLEN. A Laboratory Guide of Industrial 
Chemistry. Illustrated. 8vo. cloth. 170 pp. net, $1.50 

ROGERS, ALLEN (Editor). Industrial Chemistry. A 
manual for the student and manufacturer. Second 
Edition, thoroughly revised and enlarged. Written 
by a staff of eminent specialists. 304 illustrations. 
6/^x9^4. cloth. 1026 pp. net, $5.00 

R0HLAND, PAUL. The Colloidal and Crystalloidal State 
of Matter. Translated by W. J. Britland and H. E. 
Potts. i2mo. cloth. 54 pp. net, $1.25 



LIST OF CHEMICAL BOOKS 13 

ROTH, W. A. Exercises in Physical Chemistry. Author- 
ized translation by A. T. Cameron. 49 illustrations. 
8vo. cloth. 208 pp. net, $2.00 

SCHERER, R. Casein: Its Preparation and Technical 
Utilization. Translated from the German by Charles 
Salter. Second Edition, revised and enlarged. Il- 
lustrated. 8vo. cloth. 196 pp. net, $3.00 

SCHIDROWITZ, P. Rubber. Its Production and Indus- 
trial Uses. Plates, 83 illus. 8vo. cloth. 320 pp. 

net, $5.00 

SCHWEIZER, V. Distillation of Resins, Resinate Lakes 
and Pigments. Illustrated. 8vo. cloth. 183pp.net, $3.50 

SCOTT, W. W. Qualitative Chemical Analysis. A labo- 
ratory manual. Second Edition, thoroughly revised. 
Illus. 8vo. cloth. 180 pp. net, $1.50 

SCUDDER, HEYWARD. Electrical Conductivity and 
Ionization Constants of Organic Compounds. 6x9. 
cloth. 575 pp. net, $3.00 

SEARIE, ALFRED B. Modern Brickmaking. 260 illus- 
trations. 8vo. cloth. 449 pp. net, $5.00 

Cement, Concrete and Bricks. 113 illustrations. 

S T /2 x8}4. cloth. 415 pp. net, $3.00 

SEIDELL, A. Solubilities of Inorganic and Organic Sub- 
stances. A handbook of the most reliable quantitative 
solubility determinations. Second Printing, corrected. 
8vo. cloth. 367 pp. net, $3.00 

SENTER, G. Outlines of Physical Chemistry. Second 
Edition, revised. Illus. i2mo. cloth. 401 pp. $1.75 

— — A Text-book of Inorganic Chemistry. 90 illustra- 
tions. i2mo. cloth. 595 pp. net, $1.75 

SEXTON, A. H. Fuel and Refractory Materials. Second 
Ed., revised. 104 illus. i2mo. cloth. 374 pp. net, $2.00 

Chemistry of the Materials of Engineering. Illus. 

i2mo. cloth. 344 pp. net, $2.50 



14 D. VAN NOSTRAND COMPANY'S 

SIMMONS, W. H., and MITCHELL, C. A. Edible Fats 

and Oils. Their composition, manufacture and analy- 
sis. Illustrated. 8vo. cloth. 164 pp. net, $3.00 

SINDALL, R. W. The Manufacture of Paper. 58 illus, 
8vo. cloth. 285 pp . (Van Nostrand's Westminster 
Series.) net, $2.00 

SINDALL, R. W., and BACON, W. N. The Testing of 
Wood Pulp. A practical handbook for the pulp and 
paper trades. Illus. 8vo. cloth. 150 pp. net, $2.50 

SMITH, J. C. The Manufacture of Paint. A manual for 
paint manufacturers, merchants and painters. Second 
Edition, revised and enlarged. 80 illustrations. 5^2 x 
8%. cloth. 286 pp. net, $3.50 

SMITH, W. The Chemistry of Hat Manufacturing. 
Revised and edited by Albert Shonk. Illustrated. 
i2mo. cloth. 132 pp. net, $3.00 

S0UTHC0MBE, J. E. Chemistry of the Oil Industries. 
Illus. 8vo. cloth. 209 pp. net, $3.00 

SPEYERS, C. L. Text-book of Physical Chemistry. 20 
illustrations. 8vo. cloth. 230 pp. net, $2.25 

SPIEGEL, L. Chemical Constitution and Physiological 
Action. Translated by C. Luedeking and A. C. 
Boylston. 5x75/2. cloth. 160 pp. net, $1.25 

STEVENS, H. P. Paper Mill Chemist. 67 illustrations. 
82 tables. i6mo. cloth. 280 pp. net, $2.50 

SUDB0R0TJGH, J. J., and JAMES, J. C. Practical Or- 
ganic Chemistry. 92 illustrations. i2mo. cloth. 
394 pp. net, $2.00 

TERRY, H. L. India Rubber and Its Manufacture. 
18 illustrations. 8vo. cloth. 303 pp. (Van Nos- 
trand's Westminster Series.) net, $2.00 

TITHERLEY, A. W. Laboratory Course of Organic 
Chemistry, Including Qualitative Organic Analysis. 
Illustrated. 8vo. cloth. 235 pp. net, $2.00 

T0CH, M. Chemistry and Technology of Mixed Paints. 
New Edition. In Preparation. 



LIST OF CHEMICAL BOOKS 15 

TOCH, M. Materials for Permanent Painting. A manual 
for manufacturers, art dealers, artists, and collectors. 
With full-page plates. Illustrated. i2mo. cloth. 
208 pp. net, $2.00 

TUCKER, J. H. A Manual of Sugar Analysis. Sixth 
Edition. 43 illustrations. 8vo. cloth. 353 pp. $3.50 

UNDERWOOD, N., and SULLIVAN, T. V. Chemistry and 
Technology of Printing Inks. 9 illustrations. 6x9. 
cloth. 145 pp. net, $3.00 

VAN NOSTRAND'S Chemical Annual. Edited by John 
C. Olsen and Alfred Melhado. A handbook of useful 
data for analytical manufacturing and investigating 
chemists and chemical students. Third Issue, enlarged. 
5x7^: leather. 683 pp. net, $2.50 

VINCENT, C. Ammonia and Its Compounds. Their 
manufacture and uses. Translated from the French 
by M. J. Salter. 32 ill. 8vo. cloth. 113 pp. net, $2.00 

VON GE0RGIEVICS, G. Chemical Technology of Textile 
Fibres. Translated from the German by Charles 
Salter. 47 illustrations. 8vo. cloth. 320 pp. net, $4.50 

Chemistry of Dyestuffs. Translated from the Sec- 
ond German Edition by Charles Salter. 8vo. cloth. 
412 pp. net, $4.50 

V0SMAER, A. Ozone, Its Manufacture and Uses. 

In Press. 
WADMORE, J. M. Elementary Chemical Theory. Illus. 

i2mo. cloth. 286 pp. net, $1.50 

WALKER, JAMES. Organic Chemistry for Students of 

Medicine. Illus. 6x9. cloth. 328 pp. net, $2.50 
WALSH, J. J. Mining and Mine Ventilation. 26 illus 

8vo. cloth. 192 pp. net, $2.00 

WARNES, A. R. Coal Tar Distillation and Working Up 

of Tar Products. 6y illustrations. 5%x8%- cloth. 

197 pp. net, $2.50 



16 LIST OF CHEMICAL BOOKS 

WHITE, C. H. Methods in Metallurgical Analysis. 106 
illustrations. 5x7^. cloth. 365 pp. net, $2.50 

WILSON, F. J., and HEHBR0N, I. M. Chemical Theory 
and Calculations. An elementary text-book. Illus., 3 
folding plates. i2mo. cloth. 145 pp. net, $1.00 

WOOD, J. K. The Chemistry of Dyeing. 5x7^. cloth. 
87 pp. ( Van Nostrand's Chemical Monographs.) 

net, $0.75 

WORDEN, E. C. The Nitrocellulose Industry. A com- 
pendium of the history, chemistry, manufacture, com- 
mercial application, and analysis of nitrates, acetates, 
and xanthates of cellulose as applied to the peaceful 
arts. With a chapter on gun cotton, smokeless pow- 
der and explosive cellulose nitrates. Illustrated. 
8vo. cloth. Two volumes. 1239 pp. net, $10.00 

— — Technology of Cellulose Esters. A theoretical and 
practical treatise on the origin, history, chemistry, man- 
ufacture, technical application and aualysis of the pro- 
ducts of acylation and alkylation of normal and modi- 
fied cellulose, including nitrocellulose, celluloid, pyr- 
oxylin, collodion, celloidin, gun-cotton, acetycellulose 
and viscose, as applied to technology, pharmacy, 
microscopy, medicine, photography and the warlike 
and peaceful arts. In ten volumes. 600 ill., 12 plates, 
containing upwards of 110,000 patent and literature 
references to the work of 12,000 different investigators. 
An Exhaustive Treatise. 4000 pp. 
Vol. VIII. Carbohydrate Carboxylates (Cellulose Ace- 
tate). Illustrated. 6^x9^. 515 pp. net, $5.00 
(Other volumes to follow at short intervals.) 

WREN, HENRY. Organometallic Compounds of Zinc and 
Magnesium. 5x7^. cloth. 108 pp. (Van Nos- 
trand's Chemical Monographs.) net, $0.75 



5M— 11— 15 



